Hybrid sniffing and rebroadcast for Bluetooth networks

ABSTRACT

Disclosed herein are playback devices, groups of playback devices, and methods of operating playback devices and groupings thereof configured for hybrid sniffing and rebroadcast for networks, including Bluetooth networks.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.16/811,105 titled “Hybrid Sniffing and Rebroadcast for BluetoothNetworks,” filed on Mar. 6, 2020, and currently pending. The entirecontents of U.S. application Ser. No. 16/811,105 are incorporated hereinby reference.

FIELD OF THE DISCLOSURE

The present disclosure is related to consumer goods and, moreparticularly, to methods, systems, products, features, services, andother elements directed to media playback or some aspect thereof.

BACKGROUND

Options for accessing and listening to digital audio in an out-loudsetting were limited until in 2002, when SONOS, Inc. began developmentof a new type of playback system. Sonos then filed one of its firstpatent applications in 2003, entitled “Method for Synchronizing AudioPlayback between Multiple Networked Devices,” and began offering itsfirst media playback systems for sale in 2005. The Sonos Wireless HomeSound System enables people to experience music from many sources viaone or more networked playback devices. Through a software controlapplication installed on a controller (e.g., smartphone, tablet,computer, voice input device), one can play what she wants in any roomhaving a networked playback device. Media content (e.g., songs,podcasts, video sound) can be streamed to playback devices such thateach room with a playback device can play back corresponding differentmedia content. In addition, rooms can be grouped together forsynchronous playback of the same media content, and/or the same mediacontent can be heard in all rooms synchronously.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, aspects, and advantages of the presently disclosed technologymay be better understood with regard to the following description,appended claims, and accompanying drawings, as listed below. A personskilled in the relevant art will understand that the features shown inthe drawings are for purposes of illustrations, and variations,including different and/or additional features and arrangements thereof,are possible.

FIG. 1A shows a partial cutaway view of an environment having a mediaplayback system configured in accordance with aspects of the disclosedtechnology.

FIG. 1B shows a schematic diagram of the media playback system of FIG.1A and one or more networks.

FIG. 1C shows a block diagram of a playback device.

FIG. 1D shows a block diagram of a playback device.

FIG. 1E shows a block diagram of a network microphone device.

FIG. 1F shows a block diagram of a network microphone device.

FIG. 1G shows a block diagram of a playback device.

FIG. 1H shows a partially schematic diagram of a control device.

FIGS. 1-I through 1L show schematic diagrams of corresponding mediaplayback system zones.

FIG. 1M shows a schematic diagram of media playback system areas.

FIG. 2A shows a front isometric view of a playback device configured inaccordance with aspects of the disclosed technology.

FIG. 2B shows a front isometric view of the playback device of FIG. 3Awithout a grille.

FIG. 2C shows an exploded view of the playback device of FIG. 2A.

FIG. 3A shows a front view of a network microphone device configured inaccordance with aspects of the disclosed technology.

FIG. 3B shows a side isometric view of the network microphone device ofFIG. 3A.

FIG. 3C shows an exploded view of the network microphone device of FIGS.3A and 3B.

FIG. 3D shows an enlarged view of a portion of FIG. 3B.

FIG. 3E shows a block diagram of the network microphone device of FIGS.3A-3D

FIG. 3F shows a schematic diagram of an example voice input.

FIGS. 4A-4D show schematic diagrams of a control device in variousstages of operation in accordance with aspects of the disclosedtechnology.

FIG. 5 shows front view of a control device.

FIG. 6 shows a message flow diagram of a media playback system.

FIG. 7 shows an example configuration of a media playback systemconfigured for hybrid sniffing and rebroadcast for Bluetooth networksaccording to some embodiments.

FIG. 8 shows an example method performed by a playback device configuredfor hybrid sniffing and rebroadcast for Bluetooth networks according tosome embodiments.

The drawings are for the purpose of illustrating example embodiments,but those of ordinary skill in the art will understand that thetechnology disclosed herein is not limited to the arrangements and/orinstrumentality shown in the drawings.

DETAILED DESCRIPTION I. Overview

It is desirable to configure multiple networked media playback devices(sometimes referred to herein as playback devices or zone players) intoa playback group of playback devices configured to play audio content insynchrony with each other. A group of playback devices configured toplay audio content in synchrony with each other is sometimes referred toherein as a playback group, a synchrony group, a zone group, a bondedgroup, a bonded zone, and/or a stereo pair.

In some embodiments, one device (which may be a playback device oranother type of computing device) in a playback group is designated as agroup coordinator for the playback group and one or more other playbackdevices in the playback group are designated as group members. In someembodiments, the device designated as the group coordinator (i) obtainsaudio content for playback by the playback group, (ii) distributes theobtained audio content to the group members, and (iii) coordinatesgroupwise playback of the audio content by the playback devices in theplayback group, including but not limited to coordinating playback ofthe audio content in synchrony by the playback devices in the playbackgroup.

In some embodiments where the group coordinator is (or at leastcomprises) a playback device, the group coordinator may additionallyplay the obtained audio content in a groupwise fashion with the groupmembers. In some embodiments, the group coordinator plays the obtainedaudio content in synchrony with the other group members in the playbackgroup. But in other embodiments, the group coordinator may obtain,distribute, and coordinate groupwise and/or synchronous playback of theaudio content by the group members, but the group coordinator may notitself play the obtained audio content.

In some scenarios, the group coordinator obtains audio content forplayback by the playback group from an audio source separate from thegroup coordinator. The audio source may include a remote audio sourceaccessible via the Internet or a local audio source accessible via alocal area network (LAN) and/or a local communication link between theaudio source and the group coordinator. Examples of audio sourcesinclude streaming media (audio, video) services, digital media serversor other computing systems, voice assistant services (VAS), televisions,cable set-top-boxes, streaming media players (e.g., AppleTV, Roku,gaming console), CD/DVD players, doorbells, intercoms,telephones/smartphones, tablets, or any other source of digital audiocontent now known or later developed.

In some scenarios, the group coordinator (i) obtains audio content forplayback by the playback group via a first wireless transmission schemebetween a local audio source (e.g., a smartphone) and the groupcoordinator and (ii) distributes the obtained audio content to the groupmembers via a second wireless transmission scheme. For example, in someembodiments, the audio source transmits packets comprising audio contentto the group coordinator via an Advanced Audio Distribution Profile(A2DP) Bluetooth link, and the group coordinator distributes the audiocontent to the group members via Connectionless Slave Broadcast (CSB)Bluetooth transmission.

In some embodiments, the group coordinator and the group memberscoordinate playback of the audio content in synchrony among the groupmembers (and perhaps the group coordinator, too) via control messages(e.g., synchronous playback control messages) exchanged between thegroup coordinator and the group members. In some embodiments, the groupcoordinator transmits control messages to the group members via CSBtransmissions. In some embodiments, the group coordinator transmits (andperhaps receives) control messages to the group members via one or morewireless signaling channels which may be implemented via one or moreClassic Bluetooth and/or Bluetooth Low Energy (BLE) connections or anyother type of connection suitable for exchanging signaling informationfor coordinating and managing synchronous playback among the playbackdevices in a playback group.

This scenario has advantages over some WiFi implementations because (i)it does not require a WiFi LAN infrastructure and (ii) when at leastsome of the group members are portable, battery-powered playbackdevices, the group members can be repositioned quickly and easily in alistening environment to accommodate the preferences and/or locations oflisteners. The portability and repositionability advantages of such ascenario introduce technical challenges but also present opportunitiesfor improved networking and battery-life performance that are notpresent in scenarios where the physical positions of the group membersand/or the audio source remain fixed (or at least substantially fixed)during a playback session.

For example, because portable, battery-powered group members can berepositioned in a listening area during playback, it is possible for anindividual group member to be repositioned in a location in thelistening area where that individual group member receives CSBtransmissions from the group coordinator at a low receive power and/orwith a low signal-to-noise ratio due to signal attenuation,interference, reflections, or other wireless signal impairments.

To overcome or at least ameliorate the problems arising when anindividual portable, battery-powered group member is positioned in (orrepositioned in) a listening area where it receives CSB transmissionsfrom the group coordinator at a low receive power and/or with a lowsignal-to-noise ratio, the systems and methods disclosed herein takeadvantage of the fact that the audio source may move about the listeningarea during a playback session in combination with certain aspects ofBluetooth transmission protocols.

In particular, because the audio source in the above-described scenariomay also be repositioned in a listening area, an individual group membermay be able to receive packets transmitted via the A2DP link from theaudio source to the group coordinator at a higher receive power and/orhigher signal-to-noise ratio than the packets received from the groupcoordinator via the CSB transmissions, which may occur because either(i) the individual group member has been positioned or repositioned farfrom the group coordinator or (ii) the individual group member and/orthe audio source have been positioned (or repositioned) such that theindividual group member is closer to the audio source than the groupcoordinator. For example, if the audio source is a smartphone in aperson's hand or pocket, the audio source may move around the listeningarea as the person moves around in the listening area, and as a result,the audio source may move closer to or further from individual groupmembers over time.

To take advantage of movement of the audio source about the listeningarea during a playback session, an individual group member in someembodiments is configured to selectively receive and/or process packetsreceived via one of two streams of packets comprising audio content,where a first stream (e.g., a Bluetooth A2DP stream) is transmitted fromthe audio source via a first wireless connection and addressed to thegroup coordinator, and where a second stream (e.g., a Bluetooth CSBstream) is transmitted from the group coordinator via a second wirelessconnection and addressed to a broadcast group comprising at least theindividual group member.

In some embodiments, the group coordinator (i) receives packetscomprising audio content from an audio source via a Bluetooth A2DPstream, (ii) processes the received audio content, including determiningplayback timing for the audio content as described herein, and (iii)transmits the audio content to one or more group members via a CSBtransmission. The group coordinator also transmits synchronous playbackcontrol messages to the one or more group members. The synchronousplayback control messages may include clock timing and playback timingas described herein.

In operation, the group coordinator is configured to communicate withthe audio source via the A2DP link during a first set of transmissiontime intervals and configured to communicate with the group members viathe CSB link during a second set of transmission time intervals. In someembodiments, individual transmission time intervals in the first set oftransmission time intervals do not overlap in time with individualtransmission time intervals in the second set of transmission timeintervals. In operation, the first and second sets of transmission timeintervals comprise alternating transmit time intervals, e.g., one ormore A2DP transmit time intervals, followed by one or more CSB transmittime intervals, followed by one or more A2DP transmit time intervals,followed by one or more CSB transmit time intervals, and so on. In someembodiments, each alternate time interval is on the order of a fewmilliseconds to tens of milliseconds.

When a group member joins a playback group, the group coordinatortransmits communication configuration information to the group memberthat includes (i) information about the A2DP link (or channel) betweenthe group coordinator and the audio source and (ii) information aboutthe CSB link (or channel) between the group coordinator and the groupmembers. For an individual link (or channel), the communicationconfiguration information includes one or more of (i) a channel or linkidentifier, (ii) a frequency hopping sequence for the channel or link,(iii) a security key to decode transmissions, and/or (iv) other channelor link parameters that may be required or desired for the group memberto transmit and/or receive data via the channel/link.

In some embodiments, the channel or link identifier and/or frequencyhopping sequence for the channel or link individually or together atleast in part define transmission time intervals for transmissionsbetween Bluetooth devices. For example, in some embodiments, the groupcoordinator, individually or in combination with one or more groupmembers, determines one or more of (i) transmission time intervals forCSB transmissions from the group coordinator to the group members, (ii)transmission time intervals for Bluetooth Classic transmissions toand/or from the group members, and/or (iii) transmission time intervalsfor Bluetooth Low Energy (BLE) transmissions to and/or from the groupmembers. In some embodiments, the group coordinator additionally,individually or in combination with the audio source, determinestransmission time intervals for A2DP transmissions to and/or from theaudio source. In some embodiments, one or more (or each) of the groupcoordinator, group member(s), and/or audio source comprise a Bluetoothsubsystem (a logical or physical component) that executes one or morescheduling algorithms to determine transmission time intervals fortransmissions.

If the group member is in wireless reception range of the audio source,the group member can use the communication configuration information forthe A2DP link to “listen” to the transmissions on the A2DP link duringeach A2DP transmission time interval. Individual transmissions on theA2DP link include audio content that the audio source transmits to thegroup coordinator. If the group member receives the audio content via anA2DP transmission from the audio source during an A2DP transmission timeinterval, then the group member can save power by choosing to notreceive the audio content via a later CSB transmission from the groupcoordinator during a later CSB transmission time interval, oralternatively, if the group member received the audio content via thelater CSB transmission, the group member may choose not to process ordecode the audio content received via that later CSB transmission. Inthis manner, the group member selectively receives (or processes packetsreceived) via one of two streams of packets comprising audio content,e.g., where the first stream comprises the A2DP stream from the audiosource to the group coordinator and the second stream comprises the CSBstream from the group coordinator to the group member.

In some embodiments, selectively processing packets received via one ofthe two streams of packets comprising audio content additionally oralternatively includes the group member (i) comparing a qualitymetric(s) for a first wireless link/channel (e.g., the A2DP link) withthe quality metric(s) for the second wireless link/channel (e.g., theCSB link), (ii) in response to determining that the quality metric(s)for the first wireless link/channel is better than the quality metric(s)for the second wireless link/channel, processing packets received fromthe audio source via the first wireless link/channel and addressed tothe group coordinator, and (iii) in response to determining that thequality metric(s) for the second wireless link/channel is better thanthe quality metric(s) for the first wireless link/channel, processingpackets received from the group coordinator via the second wirelesslink/channel and addressed to a broadcast group comprising at least thegroup member. In some embodiments, if the quality metric(s) for thefirst wireless link/channel (e.g., the A2DP link) are adequate, thegroup member may choose to save power by choosing not to receive packetsvia the second wireless link/channel (e.g., the CSB link). Or if thegroup member does receive packets via the second wireless link/channel,the group member may choose not to process or decode the packetsreceived via the second wireless link/channel if the group memberpreviously received the same packets via the first wirelesslink/channel.

These and other aspects of the technical solutions disclosed hereinenable a group member to selectively receive and/or process packets ofaudio content transmitted from the audio source or transmitted from thegroup coordinator. By selectively receiving (or if received, selectivelyprocessing) packets transmitted from one of the two sources (i.e., fromthe audio source or from the group coordinator), the group member canoperate more reliably and with lower battery power consumption overtime.

For example, the group member can operate more reliably in scenarioswhere it can receive packets of audio content via the A2DP streambecause, if the group member determines that one or more packets ofaudio content received via the A2DP stream are missing or corrupt forany reason, then the group member has another opportunity to receivevalid packets of audio content in a later CSB transmission from thegroup coordinator to replace the missing or corrupt packets of audiocontent. Similarly, if the group coordinator requests that the audiosource retransmit one or more packets comprising audio content, then thegroup member has a second opportunity to receive that same audiocontent, which can improve reliability even further. Additionally, thegroup member can operate with lower battery consumption over time inscenarios where it can reliably receive packets of audio content via oneof the two streams (e.g., the A2DP and CSB streams) because, if thegroup member can receive the packets of audio content via one of thestreams, the group member can choose to not receive the packets of audiocontent via the other stream by not powering its radio receiver duringthe transmission time intervals for the other stream.

While some examples described herein may refer to functions performed bygiven actors such as “users,” “listeners,” and/or other entities, itshould be understood that this is for purposes of explanation only. Theclaims should not be interpreted to require action by any such exampleactor unless explicitly required by the language of the claimsthemselves.

In the Figures, identical reference numbers identify generally similar,and/or identical, elements. To facilitate the discussion of anyparticular element, the most significant digit or digits of a referencenumber refers to the Figure in which that element is first introduced.For example, element 110 a is first introduced and discussed withreference to FIG. 1A. Many of the details, dimensions, angles and otherfeatures shown in the Figures are merely illustrative of particularembodiments of the disclosed technology. Accordingly, other embodimentscan have other details, dimensions, angles and features withoutdeparting from the spirit or scope of the disclosure. In addition, thoseof ordinary skill in the art will appreciate that further embodiments ofthe various disclosed technologies can be practiced without several ofthe details described below.

II. Suitable Operating Environment

FIG. 1A is a partial cutaway view of a media playback system 100distributed in an environment 101 (e.g., a house). The media playbacksystem 100 comprises one or more playback devices 110 (identifiedindividually as playback devices 110 a-n), one or more networkmicrophone devices (“NMDs”), 120 (identified individually as NMDs 120a-c), and one or more control devices 130 (identified individually ascontrol devices 130 a and 130 b).

As used herein the term “playback device” can generally refer to anetwork device configured to receive, process, and output data of amedia playback system. For example, a playback device can be a networkdevice that receives and processes audio content. In some embodiments, aplayback device includes one or more transducers or speakers powered byone or more amplifiers. In other embodiments, however, a playback deviceincludes one of (or neither of) the speaker and the amplifier. Forinstance, a playback device can comprise one or more amplifiersconfigured to drive one or more speakers external to the playback devicevia a corresponding wire or cable.

Moreover, as used herein the term NMD (i.e., a “network microphonedevice”) can generally refer to a network device that is configured foraudio detection. In some embodiments, an NMD is a stand-alone deviceconfigured primarily for audio detection. In other embodiments, an NMDis incorporated into a playback device (or vice versa).

The term “control device” can generally refer to a network deviceconfigured to perform functions relevant to facilitating user access,control, and/or configuration of the media playback system 100.

Each of the playback devices 110 is configured to receive audio signalsor data from one or more media sources (e.g., one or more remoteservers, one or more local devices) and play back the received audiosignals or data as sound. The one or more NMDs 120 are configured toreceive spoken word commands, and the one or more control devices 130are configured to receive user input. In response to the received spokenword commands and/or user input, the media playback system 100 can playback audio via one or more of the playback devices 110. In certainembodiments, the playback devices 110 are configured to commenceplayback of media content in response to a trigger. For instance, one ormore of the playback devices 110 can be configured to play back amorning playlist upon detection of an associated trigger condition(e.g., presence of a user in a kitchen, detection of a coffee machineoperation). In some embodiments, for example, the media playback system100 is configured to play back audio from a first playback device (e.g.,the playback device 100 a) in synchrony with a second playback device(e.g., the playback device 100 b). Interactions between the playbackdevices 110, NMDs 120, and/or control devices 130 of the media playbacksystem 100 configured in accordance with the various embodiments of thedisclosure are described in greater detail below with respect to FIGS.1B-1L.

In the illustrated embodiment of FIG. 1A, the environment 101 comprisesa household having several rooms, spaces, and/or playback zones,including (clockwise from upper left) a master bathroom 101 a, a masterbedroom 101 b, a second bedroom 101 c, a family room or den 101 d, anoffice 101 e, a living room 101 f, a dining room 101 g, a kitchen 101 h,and an outdoor patio 101 i. While certain embodiments and examples aredescribed below in the context of a home environment, the technologiesdescribed herein may be implemented in other types of environments. Insome embodiments, for example, the media playback system 100 can beimplemented in one or more commercial settings (e.g., a restaurant,mall, airport, hotel, a retail or other store), one or more vehicles(e.g., a sports utility vehicle, bus, car, a ship, a boat, an airplane),multiple environments (e.g., a combination of home and vehicleenvironments), and/or another suitable environment where multi-zoneaudio may be desirable.

The media playback system 100 can comprise one or more playback zones,some of which may correspond to the rooms in the environment 101. Themedia playback system 100 can be established with one or more playbackzones, after which additional zones may be added, or removed to form,for example, the configuration shown in FIG. 1A. Each zone may be givena name according to a different room or space such as the office 101 e,master bathroom 101 a, master bedroom 101 b, the second bedroom 101 c,kitchen 101 h, dining room 101 g, living room 101 f, and/or the patio101 i. In some aspects, a single playback zone may include multiplerooms or spaces. In certain aspects, a single room or space may includemultiple playback zones.

In the illustrated embodiment of FIG. 1A, the master bathroom 101 a, thesecond bedroom 101 c, the office 101 e, the living room 101 f, thedining room 101 g, the kitchen 101 h, and the outdoor patio 101 i eachinclude one playback device 110, and the master bedroom 101 b and theden 101 d include a plurality of playback devices 110. In the masterbedroom 101 b, the playback devices 110 l and 110 m may be configured,for example, to play back audio content in synchrony as individual onesof playback devices 110, as a bonded playback zone, as a consolidatedplayback device, and/or any combination thereof. Similarly, in the den101 d, the playback devices 110 h-j can be configured, for instance, toplay back audio content in synchrony as individual ones of playbackdevices 110, as one or more bonded playback devices, and/or as one ormore consolidated playback devices. Additional details regarding bondedand consolidated playback devices are described below with respect to,for example, FIGS. 1B and 1E and 1I-1M.

In some aspects, one or more of the playback zones in the environment101 may each be playing different audio content. For instance, a usermay be grilling on the patio 101 i and listening to hip hop music beingplayed by the playback device 110 c while another user is preparing foodin the kitchen 101 h and listening to classical music played by theplayback device 110 b. In another example, a playback zone may play thesame audio content in synchrony with another playback zone. Forinstance, the user may be in the office 101 e listening to the playbackdevice 110 f playing back the same hip hop music being played back byplayback device 110 c on the patio 101 i. In some aspects, the playbackdevices 110 c and 110 f play back the hip hop music in synchrony suchthat the user perceives that the audio content is being playedseamlessly (or at least substantially seamlessly) while moving betweendifferent playback zones. Additional details regarding audio playbacksynchronization among playback devices and/or zones can be found, forexample, in U.S. Pat. No. 8,234,395 entitled, “System and method forsynchronizing operations among a plurality of independently clockeddigital data processing devices,” which is incorporated herein byreference in its entirety.

a. Suitable Media Playback System

FIG. 1B is a schematic diagram of the media playback system 100 and acloud network 102. For ease of illustration, certain devices of themedia playback system 100 and the cloud network 102 are omitted fromFIG. 1B. One or more communication links 103 (referred to hereinafter as“the links 103”) communicatively couple the media playback system 100and the cloud network 102.

The links 103 can comprise, for example, one or more wired networks, oneor more wireless networks, one or more wide area networks (WAN), one ormore local area networks (LAN), one or more personal area networks(PAN), one or more telecommunication networks (e.g., one or more GlobalSystem for Mobiles (GSM) networks, Code Division Multiple Access (CDMA)networks, Long-Term Evolution (LTE) networks, 5G communication networknetworks, and/or other suitable data transmission protocol networks),etc. The cloud network 102 is configured to deliver media content (e.g.,audio content, video content, photographs, social media content) to themedia playback system 100 in response to a request transmitted from themedia playback system 100 via the links 103. In some embodiments, thecloud network 102 is further configured to receive data (e.g. voiceinput data) from the media playback system 100 and correspondinglytransmit commands and/or media content to the media playback system 100.

The cloud network 102 comprises computing devices 106 (identifiedseparately as a first computing device 106 a, a second computing device106 b, and a third computing device 106 c). The computing devices 106can comprise individual computers or servers, such as, for example, amedia streaming service server storing audio and/or other media content,a voice service server, a social media server, a media playback systemcontrol server, etc. In some embodiments, one or more of the computingdevices 106 comprise modules of a single computer or server. In certainembodiments, one or more of the computing devices 106 comprise one ormore modules, computers, and/or servers. Moreover, while the cloudnetwork 102 is described above in the context of a single cloud network,in some embodiments the cloud network 102 comprises a plurality of cloudnetworks comprising communicatively coupled computing devices.Furthermore, while the cloud network 102 is shown in FIG. 1B as havingthree of the computing devices 106, in some embodiments, the cloudnetwork 102 comprises fewer (or more than) three computing devices 106.

The media playback system 100 is configured to receive media contentfrom the networks 102 via the links 103. The received media content cancomprise, for example, a Uniform Resource Identifier (URI) and/or aUniform Resource Locator (URL). For instance, in some examples, themedia playback system 100 can stream, download, or otherwise obtain datafrom a URI or a URL corresponding to the received media content. Anetwork 104 communicatively couples the links 103 and at least a portionof the devices (e.g., one or more of the playback devices 110, NMDs 120,and/or control devices 130) of the media playback system 100. Thenetwork 104 can include, for example, a wireless network (e.g., a WiFinetwork, a Bluetooth, a Z-Wave network, a ZigBee, and/or other suitablewireless communication protocol network) and/or a wired network (e.g., anetwork comprising Ethernet, Universal Serial Bus (USB), and/or anothersuitable wired communication). As those of ordinary skill in the artwill appreciate, as used herein, “WiFi” can refer to several differentcommunication protocols including, for example, Institute of Electricaland Electronics Engineers (IEEE) 802.11a, 802.11b, 802.11g, 802.11n,802.11ac, 802.11ac, 802.11ad, 802.11af, 802.11ah, 802.11ai, 802.11aj,802.11aq, 802.11ax, 802.11ay, 802.15, etc. transmitted at 2.4 Gigahertz(GHz), 5 GHz, and/or another suitable frequency.

In some embodiments, the network 104 comprises a dedicated communicationnetwork that the media playback system 100 uses to transmit messagesbetween individual devices and/or to transmit media content to and frommedia content sources (e.g., one or more of the computing devices 106).In certain embodiments, the network 104 is configured to be accessibleonly to devices in the media playback system 100, thereby reducinginterference and competition with other household devices. In otherembodiments, however, the network 104 comprises an existing householdcommunication network (e.g., a household WiFi network). In someembodiments, the links 103 and the network 104 comprise one or more ofthe same networks. In some aspects, for example, the links 103 and thenetwork 104 comprise a telecommunication network (e.g., an LTE network,a 5G network). Moreover, in some embodiments, the media playback system100 is implemented without the network 104, and devices comprising themedia playback system 100 can communicate with each other, for example,via one or more direct connections, PANs, telecommunication networks,and/or other suitable communication links.

In some embodiments, audio content sources may be regularly added orremoved from the media playback system 100. In some embodiments, forexample, the media playback system 100 performs an indexing of mediaitems when one or more media content sources are updated, added to,and/or removed from the media playback system 100. The media playbacksystem 100 can scan identifiable media items in some or all foldersand/or directories accessible to the playback devices 110, and generateor update a media content database comprising metadata (e.g., title,artist, album, track length) and other associated information (e.g.,URIs, URLs) for each identifiable media item found. In some embodiments,for example, the media content database is stored on one or more of theplayback devices 110, network microphone devices 120, and/or controldevices 130.

In the illustrated embodiment of FIG. 1B, the playback devices 110 l and110 m comprise a group 107 a. The playback devices 110 l and 110 m canbe positioned in different rooms in a household and be grouped togetherin the group 107 a on a temporary or permanent basis based on user inputreceived at the control device 130 a and/or another control device 130in the media playback system 100. When arranged in the group 107 a, theplayback devices 110 l and 110 m can be configured to play back the sameor similar audio content in synchrony from one or more audio contentsources. In certain embodiments, for example, the group 107 a comprisesa bonded zone in which the playback devices 110 l and 110 m compriseleft audio and right audio channels, respectively, of multi-channelaudio content, thereby producing or enhancing a stereo effect of theaudio content. In some embodiments, the group 107 a includes additionalplayback devices 110. In other embodiments, however, the media playbacksystem 100 omits the group 107 a and/or other grouped arrangements ofthe playback devices 110. Additional details regarding groups and otherarrangements of playback devices are described in further detail belowwith respect to FIGS. 1-I through IM.

The media playback system 100 includes the NMDs 120 a and 120 d, eachcomprising one or more microphones configured to receive voiceutterances from a user. In the illustrated embodiment of FIG. 1B, theNMD 120 a is a standalone device and the NMD 120 d is integrated intothe playback device 110 n. The NMD 120 a, for example, is configured toreceive voice input 121 from a user 123. In some embodiments, the NMD120 a transmits data associated with the received voice input 121 to avoice assistant service (VAS) configured to (i) process the receivedvoice input data and (ii) transmit a corresponding command to the mediaplayback system 100. In some aspects, for example, the computing device106 c comprises one or more modules and/or servers of a VAS (e.g., a VASoperated by one or more of SONOS®, AMAZON®, GOOGLE® APPLE®, MICROSOFT®).The computing device 106 c can receive the voice input data from the NMD120 a via the network 104 and the links 103. In response to receivingthe voice input data, the computing device 106 c processes the voiceinput data (i.e., “Play Hey Jude by The Beatles”), and determines thatthe processed voice input includes a command to play a song (e.g., “HeyJude”). The computing device 106 c accordingly transmits commands to themedia playback system 100 to play back “Hey Jude” by the Beatles from asuitable media service (e.g., via one or more of the computing devices106) on one or more of the playback devices 110.

b. Suitable Playback Devices

FIG. 1C is a block diagram of the playback device 110 a comprising aninput/output 111. The input/output 111 can include an analog I/O 111 a(e.g., one or more wires, cables, and/or other suitable communicationlinks configured to carry analog signals) and/or a digital I/O 111 b(e.g., one or more wires, cables, or other suitable communication linksconfigured to carry digital signals). In some embodiments, the analogI/O 111 a is an audio line-in input connection comprising, for example,an auto-detecting 3.5 mm audio line-in connection. In some embodiments,the digital I/O 111 b comprises a Sony/Philips Digital Interface Format(S/PDIF) communication interface and/or cable and/or a Toshiba Link(TOSLINK) cable. In some embodiments, the digital I/O 111 b comprises anHigh-Definition Multimedia Interface (HDMI) interface and/or cable. Insome embodiments, the digital I/O 111 b includes one or more wirelesscommunication links comprising, for example, a radio frequency (RF),infrared, WiFi, Bluetooth, or another suitable communication protocol.In certain embodiments, the analog I/O 111 a and the digital I/O 111 bcomprise interfaces (e.g., ports, plugs, jacks) configured to receiveconnectors of cables transmitting analog and digital signals,respectively, without necessarily including cables.

The playback device 110 a, for example, can receive media content (e.g.,audio content comprising music and/or other sounds) from a local audiosource 105 via the input/output 111 (e.g., a cable, a wire, a PAN, aBluetooth connection, an ad hoc wired or wireless communication network,and/or another suitable communication link). The local audio source 105can comprise, for example, a mobile device (e.g., a smartphone, atablet, a laptop computer) or another suitable audio component (e.g., atelevision, a desktop computer, an amplifier, a phonograph, a Blu-rayplayer, a memory storing digital media files). In some aspects, thelocal audio source 105 includes local music libraries on a smartphone, acomputer, a networked-attached storage (NAS), and/or another suitabledevice configured to store media files. In certain embodiments, one ormore of the playback devices 110, NMDs 120, and/or control devices 130comprise the local audio source 105. In other embodiments, however, themedia playback system omits the local audio source 105 altogether. Insome embodiments, the playback device 110 a does not include aninput/output 111 and receives all audio content via the network 104.

The playback device 110 a further comprises electronics 112, a userinterface 113 (e.g., one or more buttons, knobs, dials, touch-sensitivesurfaces, displays, touchscreens), and one or more transducers 114(referred to hereinafter as “the transducers 114”). The electronics 112is configured to receive audio from an audio source (e.g., the localaudio source 105) via the input/output 111, one or more of the computingdevices 106 a-c via the network 104 (FIG. 1B)), amplify the receivedaudio, and output the amplified audio for playback via one or more ofthe transducers 114. In some embodiments, the playback device 110 aoptionally includes one or more microphones 115 (e.g., a singlemicrophone, a plurality of microphones, a microphone array) (hereinafterreferred to as “the microphones 115”). In certain embodiments, forexample, the playback device 110 a having one or more of the optionalmicrophones 115 can operate as an NMD configured to receive voice inputfrom a user and correspondingly perform one or more operations based onthe received voice input.

In the illustrated embodiment of FIG. 1C, the electronics 112 compriseone or more processors 112 a (referred to hereinafter as “the processors112 a”), memory 112 b, software components 112 c, a network interface112 d, one or more audio processing components 112 g (referred tohereinafter as “the audio components 112 g”), one or more audioamplifiers 112 h (referred to hereinafter as “the amplifiers 112 h”),and power 112 i (e.g., one or more power supplies, power cables, powerreceptacles, batteries, induction coils, Power-over Ethernet (POE)interfaces, and/or other suitable sources of electric power). In someembodiments, the electronics 112 optionally include one or more othercomponents 112 j (e.g., one or more sensors, video displays,touchscreens, battery charging bases).

The processors 112 a can comprise clock-driven computing component(s)configured to process data, and the memory 112 b can comprise acomputer-readable medium (e.g., a tangible, non-transitorycomputer-readable medium, data storage loaded with one or more of thesoftware components 112 c) configured to store instructions forperforming various operations and/or functions. The processors 112 a areconfigured to execute the instructions stored on the memory 112 b toperform one or more of the operations. The operations can include, forexample, causing the playback device 110 a to retrieve audio contentfrom an audio source (e.g., one or more of the computing devices 106 a-c(FIG. 1B)), and/or another one of the playback devices 110. In someembodiments, the operations further include causing the playback device110 a to send audio content to another one of the playback devices 110 aand/or another device (e.g., one of the NMDs 120). Certain embodimentsinclude operations causing the playback device 110 a to pair withanother of the one or more playback devices 110 to enable amulti-channel audio environment (e.g., a stereo pair, a bonded zone).

The processors 112 a can be further configured to perform operationscausing the playback device 110 a to synchronize playback of audiocontent with another of the one or more playback devices 110. As thoseof ordinary skill in the art will appreciate, during synchronousplayback of audio content on a plurality of playback devices, a listenerwill preferably be unable to perceive time-delay differences betweenplayback of the audio content by the playback device 110 a and the otherone or more other playback devices 110. Additional details regardingaudio playback synchronization among playback devices can be found, forexample, in U.S. Pat. No. 8,234,395, which was incorporated by referenceabove.

In some embodiments, the memory 112 b is further configured to storedata associated with the playback device 110 a, such as one or morezones and/or zone groups of which the playback device 110 a is a member,audio sources accessible to the playback device 110 a, and/or a playbackqueue that the playback device 110 a (and/or another of the one or moreplayback devices) can be associated with. The stored data can compriseone or more state variables that are periodically updated and used todescribe a state of the playback device 110 a. The memory 112 b can alsoinclude data associated with a state of one or more of the other devices(e.g., the playback devices 110, NMDs 120, control devices 130) of themedia playback system 100. In some aspects, for example, the state datais shared during predetermined intervals of time (e.g., every 5 seconds,every 10 seconds, every 60 seconds) among at least a portion of thedevices of the media playback system 100, so that one or more of thedevices have the most recent data associated with the media playbacksystem 100.

The network interface 112 d is configured to facilitate a transmissionof data between the playback device 110 a and one or more other deviceson a data network such as, for example, the links 103 and/or the network104 (FIG. 1B). The network interface 112 d is configured to transmit andreceive data corresponding to media content (e.g., audio content, videocontent, text, photographs) and other signals (e.g., non-transitorysignals) comprising digital packet data including an Internet Protocol(IP)-based source address and/or an IP-based destination address. Thenetwork interface 112 d can parse the digital packet data such that theelectronics 112 properly receives and processes the data destined forthe playback device 110 a.

In the illustrated embodiment of FIG. 1C, the network interface 112 dcomprises one or more wireless interfaces 112 e (referred to hereinafteras “the wireless interface 112 e”). The wireless interface 112 e (e.g.,a suitable interface comprising one or more antennae) can be configuredto wirelessly communicate with one or more other devices (e.g., one ormore of the other playback devices 110, NMDs 120, and/or control devices130) that are communicatively coupled to the network 104 (FIG. 1B) inaccordance with a suitable wireless communication protocol (e.g., WiFi,Bluetooth, LTE). In some embodiments, the network interface 112 doptionally includes a wired interface 112 f (e.g., an interface orreceptacle configured to receive a network cable such as an Ethernet, aUSB-A, USB-C, and/or Thunderbolt cable) configured to communicate over awired connection with other devices in accordance with a suitable wiredcommunication protocol. In certain embodiments, the network interface112 d includes the wired interface 112 f and excludes the wirelessinterface 112 e. In some embodiments, the electronics 112 excludes thenetwork interface 112 d altogether and transmits and receives mediacontent and/or other data via another communication path (e.g., theinput/output 111).

The audio processing components 112 g are configured to process and/orfilter data comprising media content received by the electronics 112(e.g., via the input/output 111 and/or the network interface 112 d) toproduce output audio signals. In some embodiments, the audio processingcomponents 112 g comprise, for example, one or more digital-to-analogconverters (DAC), audio preprocessing components, audio enhancementcomponents, a digital signal processors (DSPs), and/or other suitableaudio processing components, modules, circuits, etc. In certainembodiments, one or more of the audio processing components 112 g cancomprise one or more subcomponents of the processors 112 a. In someembodiments, the electronics 112 omits the audio processing components112 g. In some aspects, for example, the processors 112 a executeinstructions stored on the memory 112 b to perform audio processingoperations to produce the output audio signals.

The amplifiers 112 h are configured to receive and amplify the audiooutput signals produced by the audio processing components 112 g and/orthe processors 112 a. The amplifiers 112 h can comprise electronicdevices and/or components configured to amplify audio signals to levelssufficient for driving one or more of the transducers 114. In someembodiments, for example, the amplifiers 112 h include one or moreswitching or class-D power amplifiers. In other embodiments, however,the amplifiers include one or more other types of power amplifiers(e.g., linear gain power amplifiers, class-A amplifiers, class-Bamplifiers, class-AB amplifiers, class-C amplifiers, class-D amplifiers,class-E amplifiers, class-F amplifiers, class-G and/or class Hamplifiers, and/or another suitable type of power amplifier). In certainembodiments, the amplifiers 112 h comprise a suitable combination of twoor more of the foregoing types of power amplifiers. Moreover, in someembodiments, individual ones of the amplifiers 112 h correspond toindividual ones of the transducers 114. In other embodiments, however,the electronics 112 includes a single one of the amplifiers 112 hconfigured to output amplified audio signals to a plurality of thetransducers 114. In some other embodiments, the electronics 112 omitsthe amplifiers 112 h.

The transducers 114 (e.g., one or more speakers and/or speaker drivers)receive the amplified audio signals from the amplifier 112 h and renderor output the amplified audio signals as sound (e.g., audible soundwaves having a frequency between about 20 Hertz (Hz) and 20 kilohertz(kHz)). In some embodiments, the transducers 114 can comprise a singletransducer. In other embodiments, however, the transducers 114 comprisea plurality of audio transducers. In some embodiments, the transducers114 comprise more than one type of transducer. For example, thetransducers 114 can include one or more low frequency transducers (e.g.,subwoofers, woofers), mid-range frequency transducers (e.g., mid-rangetransducers, mid-woofers), and one or more high frequency transducers(e.g., one or more tweeters). As used herein, “low frequency” cangenerally refer to audible frequencies below about 500 Hz, “mid-rangefrequency” can generally refer to audible frequencies between about 500Hz and about 2 kHz, and “high frequency” can generally refer to audiblefrequencies above 2 kHz. In certain embodiments, however, one or more ofthe transducers 114 comprise transducers that do not adhere to theforegoing frequency ranges. For example, one of the transducers 114 maycomprise a mid-woofer transducer configured to output sound atfrequencies between about 200 Hz and about 5 kHz.

By way of illustration, SONOS, Inc. presently offers (or has offered)for sale certain playback devices including, for example, a “SONOS ONE,”“PLAY:1,” “PLAY:3,” “PLAY:5,” “PLAYBAR,” “PLAYBASE,” “CONNECT:AMP,”“CONNECT,” and “SUB.” Other suitable playback devices may additionallyor alternatively be used to implement the playback devices of exampleembodiments disclosed herein. Additionally, one of ordinary skilled inthe art will appreciate that a playback device is not limited to theexamples described herein or to SONOS product offerings. In someembodiments, for example, one or more playback devices 110 compriseswired or wireless headphones (e.g., over-the-ear headphones, on-earheadphones, in-ear earphones). In other embodiments, one or more of theplayback devices 110 comprise a docking station and/or an interfaceconfigured to interact with a docking station for personal mobile mediaplayback devices. In certain embodiments, a playback device may beintegral to another device or component such as a television, a lightingfixture, or some other device for indoor or outdoor use. In someembodiments, a playback device omits a user interface and/or one or moretransducers. For example, FIG. 1D is a block diagram of a playbackdevice 110 p comprising the input/output 111 and electronics 112 withoutthe user interface 113 or transducers 114.

FIG. 1E is a block diagram of a bonded playback device 110 q comprisingthe playback device 110 a (FIG. 1C) sonically bonded with the playbackdevice 110 i (e.g., a subwoofer) (FIG. 1A). In the illustratedembodiment, the playback devices 110 a and 110 i are separate ones ofthe playback devices 110 housed in separate enclosures. In someembodiments, however, the bonded playback device 110 q comprises asingle enclosure housing both the playback devices 110 a and 110 i. Thebonded playback device 110 q can be configured to process and reproducesound differently than an unbonded playback device (e.g., the playbackdevice 110 a of FIG. 1C) and/or paired or bonded playback devices (e.g.,the playback devices 110 l and 110 m of FIG. 1B). In some embodiments,for example, the playback device 110 a is full-range playback deviceconfigured to render low frequency, mid-range frequency, and highfrequency audio content, and the playback device 110 i is a subwooferconfigured to render low frequency audio content. In some aspects, theplayback device 110 a, when bonded with the first playback device, isconfigured to render only the mid-range and high frequency components ofa particular audio content, while the playback device 110 i renders thelow frequency component of the particular audio content. In someembodiments, the bonded playback device 110 q includes additionalplayback devices and/or another bonded playback device. Additionalplayback device embodiments are described in further detail below withrespect to FIGS. 2A-3D.

c. Suitable Network Microphone Devices (NMDs)

FIG. 1F is a block diagram of the NMD 120 a (FIGS. 1A and 1B). The NMD120 a includes one or more voice processing components 124 (hereinafter“the voice components 124”) and several components described withrespect to the playback device 110 a (FIG. 1C) including the processors112 a, the memory 112 b, and the microphones 115. The NMD 120 aoptionally comprises other components also included in the playbackdevice 110 a (FIG. 1C), such as the user interface 113 and/or thetransducers 114. In some embodiments, the NMD 120 a is configured as amedia playback device (e.g., one or more of the playback devices 110),and further includes, for example, one or more of the audio processingcomponents 112 g (FIG. 1C), the transducers 114, and/or other playbackdevice components. In certain embodiments, the NMD 120 a comprises anInternet of Things (IoT) device such as, for example, a thermostat,alarm panel, fire and/or smoke detector, etc. In some embodiments, theNMD 120 a comprises the microphones 115, the voice processing 124, andonly a portion of the components of the electronics 112 described abovewith respect to FIG. 1B. In some aspects, for example, the NMD 120 aincludes the processor 112 a and the memory 112 b (FIG. 1B), whileomitting one or more other components of the electronics 112. In someembodiments, the NMD 120 a includes additional components (e.g., one ormore sensors, cameras, thermometers, barometers, hygrometers).

In some embodiments, an NMD can be integrated into a playback device.FIG. 1G is a block diagram of a playback device 110 r comprising an NMD120 d. The playback device 110 r can comprise many or all of thecomponents of the playback device 110 a and further include themicrophones 115 and voice processing 124 (FIG. 1F). The playback device110 r optionally includes an integrated control device 130 c. Thecontrol device 130 c can comprise, for example, a user interface (e.g.,the user interface 113 of FIG. 1B) configured to receive user input(e.g., touch input, voice input) without a separate control device. Inother embodiments, however, the playback device 110 r receives commandsfrom another control device (e.g., the control device 130 a of FIG. 1B).Additional NMD embodiments are described in further detail below withrespect to FIGS. 3A-3F.

Referring again to FIG. 1F, the microphones 115 are configured toacquire, capture, and/or receive sound from an environment (e.g., theenvironment 101 of FIG. 1A) and/or a room in which the NMD 120 a ispositioned. The received sound can include, for example, vocalutterances, audio played back by the NMD 120 a and/or another playbackdevice, background voices, ambient sounds, etc. The microphones 115convert the received sound into electrical signals to produce microphonedata. The voice processing 124 receives and analyzes the microphone datato determine whether a voice input is present in the microphone data.The voice input can comprise, for example, an activation word followedby an utterance including a user request. As those of ordinary skill inthe art will appreciate, an activation word is a word or other audio cuethat signifying a user voice input. For instance, in querying theAMAZON® VAS, a user might speak the activation word “Alexa.” Otherexamples include “Ok, Google” for invoking the GOOGLE® VAS and “Hey,Siri” for invoking the APPLE® VAS.

After detecting the activation word, voice processing 124 monitors themicrophone data for an accompanying user request in the voice input. Theuser request may include, for example, a command to control athird-party device, such as a thermostat (e.g., NEST® thermostat), anillumination device (e.g., a PHILIPS HUE® lighting device), or a mediaplayback device (e.g., a Sonos® playback device). For example, a usermight speak the activation word “Alexa” followed by the utterance “setthe thermostat to 68 degrees” to set a temperature in a home (e.g., theenvironment 101 of FIG. 1A). The user might speak the same activationword followed by the utterance “turn on the living room” to turn onillumination devices in a living room area of the home. The user maysimilarly speak an activation word followed by a request to play aparticular song, an album, or a playlist of music on a playback devicein the home. Additional description regarding receiving and processingvoice input data can be found in further detail below with respect toFIGS. 3A-3F.

d. Suitable Control Devices

FIG. 1H is a partially schematic diagram of the control device 130 a(FIGS. 1A and 1B). As used herein, the term “control device” can be usedinterchangeably with “controller” or “control system.” Among otherfeatures, the control device 130 a is configured to receive user inputrelated to the media playback system 100 and, in response, cause one ormore devices in the media playback system 100 to perform an action(s) oroperation(s) corresponding to the user input. In the illustratedembodiment, the control device 130 a comprises a smartphone (e.g., aniPhone™, an Android phone) on which media playback system controllerapplication software is installed. In some embodiments, the controldevice 130 a comprises, for example, a tablet (e.g., an iPad™), acomputer (e.g., a laptop computer, a desktop computer), and/or anothersuitable device (e.g., a television, an automobile audio head unit, anIoT device). In certain embodiments, the control device 130 a comprisesa dedicated controller for the media playback system 100. In otherembodiments, as described above with respect to FIG. 1G, the controldevice 130 a is integrated into another device in the media playbacksystem 100 (e.g., one more of the playback devices 110, NMDs 120, and/orother suitable devices configured to communicate over a network).

The control device 130 a includes electronics 132, a user interface 133,one or more speakers 134, and one or more microphones 135. Theelectronics 132 comprise one or more processors 132 a (referred tohereinafter as “the processors 132 a”), a memory 132 b, softwarecomponents 132 c, and a network interface 132 d. The processor 132 a canbe configured to perform functions relevant to facilitating user access,control, and configuration of the media playback system 100. The memory132 b can comprise data storage that can be loaded with one or more ofthe software components executable by the processor 302 to perform thosefunctions. The software components 132 c can comprise applicationsand/or other executable software configured to facilitate control of themedia playback system 100. The memory 112 b can be configured to store,for example, the software components 132 c, media playback systemcontroller application software, and/or other data associated with themedia playback system 100 and the user.

The network interface 132 d is configured to facilitate networkcommunications between the control device 130 a and one or more otherdevices in the media playback system 100, and/or one or more remotedevices. In some embodiments, the network interface 132 d is configuredto operate according to one or more suitable communication industrystandards (e.g., infrared, radio, wired standards including IEEE 802.3,wireless standards including IEEE 802.11a, 802.11b, 802.11g, 802.11n,802.11ac, 802.15, 4G, LTE). The network interface 132 d can beconfigured, for example, to transmit data to and/or receive data fromthe playback devices 110, the NMDs 120, other ones of the controldevices 130, one of the computing devices 106 of FIG. 1B, devicescomprising one or more other media playback systems, etc. Thetransmitted and/or received data can include, for example, playbackdevice control commands, state variables, playback zone and/or zonegroup configurations. For instance, based on user input received at theuser interface 133, the network interface 132 d can transmit a playbackdevice control command (e.g., volume control, audio playback control,audio content selection) from the control device 304 to one or more ofplayback devices. The network interface 132 d can also transmit and/orreceive configuration changes such as, for example, adding/removing oneor more playback devices to/from a zone, adding/removing one or morezones to/from a zone group, forming a bonded or consolidated player,separating one or more playback devices from a bonded or consolidatedplayer, among others. Additional description of zones and groups can befound below with respect to FIGS. 1-I through 1M.

The user interface 133 is configured to receive user input and canfacilitate control of the media playback system 100. The user interface133 includes media content art 133 a (e.g., album art, lyrics, videos),a playback status indicator 133 b (e.g., an elapsed and/or remainingtime indicator), media content information region 133 c, a playbackcontrol region 133 d, and a zone indicator 133 e. The media contentinformation region 133 c can include a display of relevant information(e.g., title, artist, album, genre, release year) about media contentcurrently playing and/or media content in a queue or playlist. Theplayback control region 133 d can include selectable (e.g., via touchinput and/or via a cursor or another suitable selector) icons to causeone or more playback devices in a selected playback zone or zone groupto perform playback actions such as, for example, play or pause, fastforward, rewind, skip to next, skip to previous, enter/exit shufflemode, enter/exit repeat mode, enter/exit cross fade mode, etc. Theplayback control region 133 d may also include selectable icons tomodify equalization settings, playback volume, and/or other suitableplayback actions. In the illustrated embodiment, the user interface 133comprises a display presented on a touch screen interface of asmartphone (e.g., an iPhone™, an Android phone). In some embodiments,however, user interfaces of varying formats, styles, and interactivesequences may alternatively be implemented on one or more networkdevices to provide comparable control access to a media playback system.

The one or more speakers 134 (e.g., one or more transducers) can beconfigured to output sound to the user of the control device 130 a. Insome embodiments, the one or more speakers comprise individualtransducers configured to correspondingly output low frequencies,mid-range frequencies, and/or high frequencies. In some aspects, forexample, the control device 130 a is configured as a playback device(e.g., one of the playback devices 110). Similarly, in some embodimentsthe control device 130 a is configured as an NMD (e.g., one of the NMDs120), receiving voice commands and other sounds via the one or moremicrophones 135.

The one or more microphones 135 can comprise, for example, one or morecondenser microphones, electret condenser microphones, dynamicmicrophones, and/or other suitable types of microphones or transducers.In some embodiments, two or more of the microphones 135 are arranged tocapture location information of an audio source (e.g., voice, audiblesound) and/or configured to facilitate filtering of background noise.Moreover, in certain embodiments, the control device 130 a is configuredto operate as playback device and an NMD. In other embodiments, however,the control device 130 a omits the one or more speakers 134 and/or theone or more microphones 135. For instance, the control device 130 a maycomprise a device (e.g., a thermostat, an IoT device, a network device)comprising a portion of the electronics 132 and the user interface 133(e.g., a touch screen) without any speakers or microphones. Additionalcontrol device embodiments are described in further detail below withrespect to FIGS. 4A-4D and 5.

e. Suitable Playback Device Configurations

FIGS. 1-1 through 1M show example configurations of playback devices inzones and zone groups. Referring first to FIG. 1M, in one example, asingle playback device may belong to a zone. For example, the playbackdevice 110 g in the second bedroom 101 c (FIG. 1A) may belong to Zone C.In some implementations described below, multiple playback devices maybe “bonded” to form a “bonded pair” which together form a single zone.For example, the playback device 110 l (e.g., a left playback device)can be bonded to the playback device 110 l (e.g., a left playbackdevice) to form Zone A. Bonded playback devices may have differentplayback responsibilities (e.g., channel responsibilities). In anotherimplementation described below, multiple playback devices may be mergedto form a single zone. For example, the playback device 110 h (e.g., afront playback device) may be merged with the playback device 110 i(e.g., a subwoofer), and the playback devices 110 j and 110 k (e.g.,left and right surround speakers, respectively) to form a single Zone D.In another example, the playback devices 110 g and 110 h can be bemerged to form a merged group or a zone group 108 b. The merged playbackdevices 110 g and 110 h may not be specifically assigned differentplayback responsibilities. That is, the merged playback devices 110 hand 110 i may, aside from playing audio content in synchrony, each playaudio content as they would if they were not merged.

Each zone in the media playback system 100 may be provided for controlas a single user interface (UI) entity. For example, Zone A may beprovided as a single entity named Master Bathroom. Zone B may beprovided as a single entity named Master Bedroom. Zone C may be providedas a single entity named Second Bedroom.

Playback devices that are bonded may have different playbackresponsibilities, such as responsibilities for certain audio channels.For example, as shown in FIG. 1-I, the playback devices 110 l and 110 mmay be bonded so as to produce or enhance a stereo effect of audiocontent. In this example, the playback device 110 l may be configured toplay a left channel audio component, while the playback device 110 k maybe configured to play a right channel audio component. In someimplementations, such stereo bonding may be referred to as “pairing.”

Additionally, bonded playback devices may have additional and/ordifferent respective speaker drivers. As shown in FIG. 1J, the playbackdevice 110 h named Front may be bonded with the playback device 110 inamed SUB. The Front device 110 h can be configured to render a range ofmid to high frequencies and the SUB device 110 i can be configuredrender low frequencies. When unbonded, however, the Front device 110 hcan be configured render a full range of frequencies. As anotherexample, FIG. 1K shows the Front and SUB devices 110 h and 110 i furtherbonded with Left and Right playback devices 110 j and 110 k,respectively. In some implementations, the Right and Left devices 110 jand 102 k can be configured to form surround or “satellite” channels ofa home theater system. The bonded playback devices 110 h, 110 i, 110 j,and 110 k may form a single Zone D (FIG. 1M).

Playback devices that are merged may not have assigned playbackresponsibilities, and may each render the full range of audio contentthe respective playback device is capable of. Nevertheless, mergeddevices may be represented as a single UI entity (i.e., a zone, asdiscussed above). For instance, the playback devices 110 a and 110 n themaster bathroom have the single UI entity of Zone A. In one embodiment,the playback devices 110 a and 110 n may each output the full range ofaudio content each respective playback devices 110 a and 110 n arecapable of, in synchrony.

In some embodiments, an NMD is bonded or merged with another device soas to form a zone. For example, the NMD 120 b may be bonded with theplayback device 110 e, which together form Zone F, named Living Room. Inother embodiments, a stand-alone network microphone device may be in azone by itself. In other embodiments, however, a stand-alone networkmicrophone device may not be associated with a zone. Additional detailsregarding associating network microphone devices and playback devices asdesignated or default devices may be found, for example, in previouslyreferenced U.S. patent application Ser. No. 15/438,749.

Zones of individual, bonded, and/or merged devices may be grouped toform a zone group. For example, referring to FIG. 1M, Zone A may begrouped with Zone B to form a zone group 108 a that includes the twozones. Similarly, Zone G may be grouped with Zone H to form the zonegroup 108 b. As another example, Zone A may be grouped with one or moreother Zones C-I. The Zones A-I may be grouped and ungrouped in numerousways. For example, three, four, five, or more (e.g., all) of the ZonesA-I may be grouped. When grouped, the zones of individual and/or bondedplayback devices may play back audio in synchrony with one another, asdescribed in previously referenced U.S. Pat. No. 8,234,395. Playbackdevices may be dynamically grouped and ungrouped to form new ordifferent groups that synchronously play back audio content.

In various implementations, the zones in an environment may be thedefault name of a zone within the group or a combination of the names ofthe zones within a zone group. For example, Zone Group 108 b can have beassigned a name such as “Dining+Kitchen”, as shown in FIG. 1M. In someembodiments, a zone group may be given a unique name selected by a user.

Certain data may be stored in a memory of a playback device (e.g., thememory 112 b of FIG. 1C) as one or more state variables that areperiodically updated and used to describe the state of a playback zone,the playback device(s), and/or a zone group associated therewith. Thememory may also include the data associated with the state of the otherdevices of the media system, and shared from time to time among thedevices so that one or more of the devices have the most recent dataassociated with the system.

In some embodiments, the memory may store instances of various variabletypes associated with the states. Variables instances may be stored withidentifiers (e.g., tags) corresponding to type. For example, certainidentifiers may be a first type “a1” to identify playback device(s) of azone, a second type “b1” to identify playback device(s) that may bebonded in the zone, and a third type “c1” to identify a zone group towhich the zone may belong. As a related example, identifiers associatedwith the second bedroom 101 c may indicate that the playback device isthe only playback device of the Zone C and not in a zone group.Identifiers associated with the Den may indicate that the Den is notgrouped with other zones but includes bonded playback devices 110 h-110k. Identifiers associated with the Dining Room may indicate that theDining Room is part of the Dining+Kitchen zone group 108 b and thatdevices 110 b and 110 d are grouped (FIG. 1L). Identifiers associatedwith the Kitchen may indicate the same or similar information by virtueof the Kitchen being part of the Dining+Kitchen zone group 108 b. Otherexample zone variables and identifiers are described below.

In yet another example, the media playback system 100 may variables oridentifiers representing other associations of zones and zone groups,such as identifiers associated with Areas, as shown in FIG. 1M. An areamay involve a cluster of zone groups and/or zones not within a zonegroup. For instance, FIG. 1M shows an Upper Area 109 a including ZonesA-D, and a Lower Area 109 b including Zones E-I. In one aspect, an Areamay be used to invoke a cluster of zone groups and/or zones that shareone or more zones and/or zone groups of another cluster. In anotheraspect, this differs from a zone group, which does not share a zone withanother zone group. Further examples of techniques for implementingAreas may be found, for example, in U.S. application Ser. No. 15/682,506filed Aug. 21, 2017 and titled “Room Association Based on Name,” andU.S. Pat. No. 8,483,853 filed Sep. 11, 2007, and titled “Controlling andmanipulating groupings in a multi-zone media system.” Each of theseapplications is incorporated herein by reference in its entirety. Insome embodiments, the media playback system 100 may not implement Areas,in which case the system may not store variables associated with Areas.

III. Example Systems and Devices

FIG. 2A is a front isometric view of a playback device 210 configured inaccordance with aspects of the disclosed technology. FIG. 2B is a frontisometric view of the playback device 210 without a grille 216 e. FIG.2C is an exploded view of the playback device 210. Referring to FIGS.2A-2C together, the playback device 210 comprises a housing 216 thatincludes an upper portion 216 a, a right or first side portion 216 b, alower portion 216 c, a left or second side portion 216 d, the grille 216e, and a rear portion 216 f A plurality of fasteners 216 g (e.g., one ormore screws, rivets, clips) attaches a frame 216 h to the housing 216. Acavity 216 j (FIG. 2C) in the housing 216 is configured to receive theframe 216 h and electronics 212. The frame 216 h is configured to carrya plurality of transducers 214 (identified individually in FIG. 2B astransducers 214 a-f). The electronics 212 (e.g., the electronics 112 ofFIG. 1C) is configured to receive audio content from an audio source andsend electrical signals corresponding to the audio content to thetransducers 214 for playback.

The transducers 214 are configured to receive the electrical signalsfrom the electronics 112, and further configured to convert the receivedelectrical signals into audible sound during playback. For instance, thetransducers 214 a-c (e.g., tweeters) can be configured to output highfrequency sound (e.g., sound waves having a frequency greater than about2 kHz). The transducers 214 d-f (e.g., mid-woofers, woofers, midrangespeakers) can be configured output sound at frequencies lower than thetransducers 214 a-c (e.g., sound waves having a frequency lower thanabout 2 kHz). In some embodiments, the playback device 210 includes anumber of transducers different than those illustrated in FIGS. 2A-2C.For example, as described in further detail below with respect to FIGS.3A-3C, the playback device 210 can include fewer than six transducers(e.g., one, two, three). In other embodiments, however, the playbackdevice 210 includes more than six transducers (e.g., nine, ten).Moreover, in some embodiments, all or a portion of the transducers 214are configured to operate as a phased array to desirably adjust (e.g.,narrow or widen) a radiation pattern of the transducers 214, therebyaltering a user's perception of the sound emitted from the playbackdevice 210.

In the illustrated embodiment of FIGS. 2A-2C, a filter 216 i is axiallyaligned with the transducer 214 b. The filter 216 i can be configured todesirably attenuate a predetermined range of frequencies that thetransducer 214 b outputs to improve sound quality and a perceived soundstage output collectively by the transducers 214. In some embodiments,however, the playback device 210 omits the filter 216 i. In otherembodiments, the playback device 210 includes one or more additionalfilters aligned with the transducers 214 b and/or at least another ofthe transducers 214.

FIGS. 3A and 3B are front and right isometric side views, respectively,of an NMD 320 configured in accordance with embodiments of the disclosedtechnology. FIG. 3C is an exploded view of the NMD 320. FIG. 3D is anenlarged view of a portion of FIG. 3B including a user interface 313 ofthe NMD 320. Referring first to FIGS. 3A-3C, the NMD 320 includes ahousing 316 comprising an upper portion 316 a, a lower portion 316 b andan intermediate portion 316 c (e.g., a grille). A plurality of ports,holes or apertures 316 d in the upper portion 316 a allow sound to passthrough to one or more microphones 315 (FIG. 3C) positioned within thehousing 316. The one or more microphones 316 are configured to receivedsound via the apertures 316 d and produce electrical signals based onthe received sound. In the illustrated embodiment, a frame 316 e (FIG.3C) of the housing 316 surrounds cavities 316 f and 316 g configured tohouse, respectively, a first transducer 314 a (e.g., a tweeter) and asecond transducer 314 b (e.g., a mid-woofer, a midrange speaker, awoofer). In other embodiments, however, the NMD 320 includes a singletransducer, or more than two (e.g., two, five, six) transducers. Incertain embodiments, the NMD 320 omits the transducers 314 a and 314 baltogether.

Electronics 312 (FIG. 3C) includes components configured to drive thetransducers 314 a and 314 b, and further configured to analyze audiocontent corresponding to the electrical signals produced by the one ormore microphones 315. In some embodiments, for example, the electronics312 comprises many or all of the components of the electronics 112described above with respect to FIG. 1C. In certain embodiments, theelectronics 312 includes components described above with respect to FIG.1F such as, for example, the one or more processors 112 a, the memory112 b, the software components 112 c, the network interface 112 d, etc.In some embodiments, the electronics 312 includes additional suitablecomponents (e.g., proximity or other sensors).

Referring to FIG. 3D, the user interface 313 includes a plurality ofcontrol surfaces (e.g., buttons, knobs, capacitive surfaces) including afirst control surface 313 a (e.g., a previous control), a second controlsurface 313 b (e.g., a next control), and a third control surface 313 c(e.g., a play and/or pause control). A fourth control surface 313 d isconfigured to receive touch input corresponding to activation anddeactivation of the one or microphones 315. A first indicator 313 e(e.g., one or more light emitting diodes (LEDs) or another suitableilluminator) can be configured to illuminate only when the one or moremicrophones 315 are activated. A second indicator 313 f (e.g., one ormore LEDs) can be configured to remain solid during normal operation andto blink or otherwise change from solid to indicate a detection of voiceactivity. In some embodiments, the user interface 313 includesadditional or fewer control surfaces and illuminators. In oneembodiment, for example, the user interface 313 includes the firstindicator 313 e, omitting the second indicator 313 f Moreover, incertain embodiments, the NMD 320 comprises a playback device and acontrol device, and the user interface 313 comprises the user interfaceof the control device.

Referring to FIGS. 3A-3D together, the NMD 320 is configured to receivevoice commands from one or more adjacent users via the one or moremicrophones 315. As described above with respect to FIG. 1B, the one ormore microphones 315 can acquire, capture, or record sound in a vicinity(e.g., a region within 10 m or less of the NMD 320) and transmitelectrical signals corresponding to the recorded sound to theelectronics 312. The electronics 312 can process the electrical signalsand can analyze the resulting audio data to determine a presence of oneor more voice commands (e.g., one or more activation words). In someembodiments, for example, after detection of one or more suitable voicecommands, the NMD 320 is configured to transmit a portion of therecorded audio data to another device and/or a remote server (e.g., oneor more of the computing devices 106 of FIG. 1B) for further analysis.The remote server can analyze the audio data, determine an appropriateaction based on the voice command, and transmit a message to the NMD 320to perform the appropriate action. For instance, a user may speak“Sonos, play Michael Jackson.” The NMD 320 can, via the one or moremicrophones 315, record the user's voice utterance, determine thepresence of a voice command, and transmit the audio data having thevoice command to a remote server (e.g., one or more of the remotecomputing devices 106 of FIG. 1B, one or more servers of a VAS and/oranother suitable service). The remote server can analyze the audio dataand determine an action corresponding to the command. The remote servercan then transmit a command to the NMD 320 to perform the determinedaction (e.g., play back audio content related to Michael Jackson). TheNMD 320 can receive the command and play back the audio content relatedto Michael Jackson from a media content source. As described above withrespect to FIG. 1B, suitable content sources can include a device orstorage communicatively coupled to the NMD 320 via a LAN (e.g., thenetwork 104 of FIG. 1B), a remote server (e.g., one or more of theremote computing devices 106 of FIG. 1B), etc. In certain embodiments,however, the NMD 320 determines and/or performs one or more actionscorresponding to the one or more voice commands without intervention orinvolvement of an external device, computer, or server.

FIG. 3E is a functional block diagram showing additional features of theNMD 320 in accordance with aspects of the disclosure. The NMD 320includes components configured to facilitate voice command captureincluding voice activity detector component(s) 312 k, beam formercomponents 3121, acoustic echo cancellation (AEC) and/or self-soundsuppression components 312 m, activation word detector components 312 n,and voice/speech conversion components 312 o (e.g., voice-to-text andtext-to-voice). In the illustrated embodiment of FIG. 3E, the foregoingcomponents 312 k-312 o are shown as separate components. In someembodiments, however, one or more of the components 312 k-312 o aresubcomponents of the processors 112 a.

The beamforming and self-sound suppression components 312 l and 312 mare configured to detect an audio signal and determine aspects of voiceinput represented in the detected audio signal, such as the direction,amplitude, frequency spectrum, etc. The voice activity detector activitycomponents 312 k are operably coupled with the beamforming and AECcomponents 312 l and 312 m and are configured to determine a directionand/or directions from which voice activity is likely to have occurredin the detected audio signal. Potential speech directions can beidentified by monitoring metrics which distinguish speech from othersounds. Such metrics can include, for example, energy within the speechband relative to background noise and entropy within the speech band,which is measure of spectral structure. As those of ordinary skill inthe art will appreciate, speech typically has a lower entropy than mostcommon background noise. The activation word detector components 312 nare configured to monitor and analyze received audio to determine if anyactivation words (e.g., wake words) are present in the received audio.The activation word detector components 312 n may analyze the receivedaudio using an activation word detection algorithm. If the activationword detector 312 n detects an activation word, the NMD 320 may processvoice input contained in the received audio. Example activation worddetection algorithms accept audio as input and provide an indication ofwhether an activation word is present in the audio. Many first- andthird-party activation word detection algorithms are known andcommercially available. For instance, operators of a voice service maymake their algorithm available for use in third-party devices.Alternatively, an algorithm may be trained to detect certain activationwords. In some embodiments, the activation word detector 312 n runsmultiple activation word detection algorithms on the received audiosimultaneously (or substantially simultaneously). As noted above,different voice services (e.g. AMAZON's ALEXA®, APPLE's SIRI®, orMICROSOFT's CORTANA®) can each use a different activation word forinvoking their respective voice service. To support multiple services,the activation word detector 312 n may run the received audio throughthe activation word detection algorithm for each supported voice servicein parallel.

The speech/text conversion components 312 o may facilitate processing byconverting speech in the voice input to text. In some embodiments, theelectronics 312 can include voice recognition software that is trainedto a particular user or a particular set of users associated with ahousehold. Such voice recognition software may implementvoice-processing algorithms that are tuned to specific voice profile(s).Tuning to specific voice profiles may require less computationallyintensive algorithms than traditional voice activity services, whichtypically sample from a broad base of users and diverse requests thatare not targeted to media playback systems.

FIG. 3F is a schematic diagram of an example voice input 328 captured bythe NMD 320 in accordance with aspects of the disclosure. The voiceinput 328 can include a activation word portion 328 a and a voiceutterance portion 328 b. In some embodiments, the activation word 557 acan be a known activation word, such as “Alexa,” which is associatedwith AMAZON's ALEXA®. In other embodiments, however, the voice input 328may not include a activation word. In some embodiments, a networkmicrophone device may output an audible and/or visible response upondetection of the activation word portion 328 a. In addition oralternately, an NMB may output an audible and/or visible response afterprocessing a voice input and/or a series of voice inputs.

The voice utterance portion 328 b may include, for example, one or morespoken commands (identified individually as a first command 328 c and asecond command 328 e) and one or more spoken keywords (identifiedindividually as a first keyword 328 d and a second keyword 328 f). Inone example, the first command 328 c can be a command to play music,such as a specific song, album, playlist, etc. In this example, thekeywords may be one or words identifying one or more zones in which themusic is to be played, such as the Living Room and the Dining Room shownin FIG. 1A. In some examples, the voice utterance portion 328 b caninclude other information, such as detected pauses (e.g., periods ofnon-speech) between words spoken by a user, as shown in FIG. 3F. Thepauses may demarcate the locations of separate commands, keywords, orother information spoke by the user within the voice utterance portion328 b.

In some embodiments, the media playback system 100 is configured totemporarily reduce the volume of audio content that it is playing whiledetecting the activation word portion 557 a. The media playback system100 may restore the volume after processing the voice input 328, asshown in FIG. 3F. Such a process can be referred to as ducking, examplesof which are disclosed in U.S. patent application Ser. No. 15/438,749,incorporated by reference herein in its entirety.

FIGS. 4A-4D are schematic diagrams of a control device 430 (e.g., thecontrol device 130 a of FIG. 1H, a smartphone, a tablet, a dedicatedcontrol device, an IoT device, and/or another suitable device) showingcorresponding user interface displays in various states of operation. Afirst user interface display 431 a (FIG. 4A) includes a display name 433a (i.e., “Rooms”). A selected group region 433 b displays audio contentinformation (e.g., artist name, track name, album art) of audio contentplayed back in the selected group and/or zone. Group regions 433 c and433 d display corresponding group and/or zone name, and audio contentinformation audio content played back or next in a playback queue of therespective group or zone. An audio content region 433 e includesinformation related to audio content in the selected group and/or zone(i.e., the group and/or zone indicated in the selected group region 433b). A lower display region 433 f is configured to receive touch input todisplay one or more other user interface displays. For example, if auser selects “Browse” in the lower display region 433 f, the controldevice 430 can be configured to output a second user interface display431 b (FIG. 4B) comprising a plurality of music services 433 g (e.g.,Spotify, Radio by Tunein, Apple Music, Pandora, Amazon, TV, local music,line-in) through which the user can browse and from which the user canselect media content for play back via one or more playback devices(e.g., one of the playback devices 110 of FIG. 1A). Alternatively, ifthe user selects “My Sonos” in the lower display region 433 f, thecontrol device 430 can be configured to output a third user interfacedisplay 431 c (FIG. 4C). A first media content region 433 h can includegraphical representations (e.g., album art) corresponding to individualalbums, stations, or playlists. A second media content region 433 i caninclude graphical representations (e.g., album art) corresponding toindividual songs, tracks, or other media content. If the user selectionsa graphical representation 433 j (FIG. 4C), the control device 430 canbe configured to begin play back of audio content corresponding to thegraphical representation 433 j and output a fourth user interfacedisplay 431 d fourth user interface display 431 d includes an enlargedversion of the graphical representation 433 j, media content information433 k (e.g., track name, artist, album), transport controls 433 m (e.g.,play, previous, next, pause, volume), and indication 433 n of thecurrently selected group and/or zone name.

FIG. 5 is a schematic diagram of a control device 530 (e.g., a laptopcomputer, a desktop computer). The control device 530 includestransducers 534, a microphone 535, and a camera 536. A user interface531 includes a transport control region 533 a, a playback status region533 b, a playback zone region 533 c, a playback queue region 533 d, anda media content source region 533 e. The transport control regioncomprises one or more controls for controlling media playback including,for example, volume, previous, play/pause, next, repeat, shuffle, trackposition, crossfade, equalization, etc. The audio content source region533 e includes a listing of one or more media content sources from whicha user can select media items for play back and/or adding to a playbackqueue.

The playback zone region 533 b can include representations of playbackzones within the media playback system 100 (FIGS. 1A and 1B). In someembodiments, the graphical representations of playback zones may beselectable to bring up additional selectable icons to manage orconfigure the playback zones in the media playback system, such as acreation of bonded zones, creation of zone groups, separation of zonegroups, renaming of zone groups, etc. In the illustrated embodiment, a“group” icon is provided within each of the graphical representations ofplayback zones. The “group” icon provided within a graphicalrepresentation of a particular zone may be selectable to bring upoptions to select one or more other zones in the media playback systemto be grouped with the particular zone. Once grouped, playback devicesin the zones that have been grouped with the particular zone can beconfigured to play audio content in synchrony with the playbackdevice(s) in the particular zone. Analogously, a “group” icon may beprovided within a graphical representation of a zone group. In theillustrated embodiment, the “group” icon may be selectable to bring upoptions to deselect one or more zones in the zone group to be removedfrom the zone group. In some embodiments, the control device 530includes other interactions and implementations for grouping andungrouping zones via the user interface 531. In certain embodiments, therepresentations of playback zones in the playback zone region 533 b canbe dynamically updated as playback zone or zone group configurations aremodified.

The playback status region 533 c includes graphical representations ofaudio content that is presently being played, previously played, orscheduled to play next in the selected playback zone or zone group. Theselected playback zone or zone group may be visually distinguished onthe user interface, such as within the playback zone region 533 b and/orthe playback queue region 533 d. The graphical representations mayinclude track title, artist name, album name, album year, track length,and other relevant information that may be useful for the user to knowwhen controlling the media playback system 100 via the user interface531.

The playback queue region 533 d includes graphical representations ofaudio content in a playback queue associated with the selected playbackzone or zone group. In some embodiments, each playback zone or zonegroup may be associated with a playback queue containing informationcorresponding to zero or more audio items for playback by the playbackzone or zone group. For instance, each audio item in the playback queuemay comprise a uniform resource identifier (URI), a uniform resourcelocator (URL) or some other identifier that may be used by a playbackdevice in the playback zone or zone group to find and/or retrieve theaudio item from a local audio content source or a networked audiocontent source, possibly for playback by the playback device. In someembodiments, for example, a playlist can be added to a playback queue,in which information corresponding to each audio item in the playlistmay be added to the playback queue. In some embodiments, audio items ina playback queue may be saved as a playlist. In certain embodiments, aplayback queue may be empty, or populated but “not in use” when theplayback zone or zone group is playing continuously streaming audiocontent, such as Internet radio that may continue to play untilotherwise stopped, rather than discrete audio items that have playbackdurations. In some embodiments, a playback queue can include Internetradio and/or other streaming audio content items and be “in use” whenthe playback zone or zone group is playing those items.

When playback zones or zone groups are “grouped” or “ungrouped,”playback queues associated with the affected playback zones or zonegroups may be cleared or re-associated. For example, if a first playbackzone including a first playback queue is grouped with a second playbackzone including a second playback queue, the established zone group mayhave an associated playback queue that is initially empty, that containsaudio items from the first playback queue (such as if the secondplayback zone was added to the first playback zone), that contains audioitems from the second playback queue (such as if the first playback zonewas added to the second playback zone), or a combination of audio itemsfrom both the first and second playback queues. Subsequently, if theestablished zone group is ungrouped, the resulting first playback zonemay be re-associated with the previous first playback queue, or beassociated with a new playback queue that is empty or contains audioitems from the playback queue associated with the established zone groupbefore the established zone group was ungrouped. Similarly, theresulting second playback zone may be re-associated with the previoussecond playback queue, or be associated with a new playback queue thatis empty, or contains audio items from the playback queue associatedwith the established zone group before the established zone group wasungrouped.

FIG. 6 is a message flow diagram illustrating data exchanges betweendevices of the media playback system 100 (FIGS. 1A-1M).

At step 650 a, the media playback system 100 receives an indication ofselected media content (e.g., one or more songs, albums, playlists,podcasts, videos, stations) via the control device 130 a. The selectedmedia content can comprise, for example, media items stored locally onor more devices (e.g., the audio source 105 of FIG. 1C) connected to themedia playback system and/or media items stored on one or more mediaservice servers (one or more of the remote computing devices 106 of FIG.1B). In response to receiving the indication of the selected mediacontent, the control device 130 a transmits a message 651 a to theplayback device 110 a (FIGS. 1A-1C) to add the selected media content toa playback queue on the playback device 110 a.

At step 650 b, the playback device 110 a receives the message 651 a andadds the selected media content to the playback queue for play back.

At step 650 c, the control device 130 a receives input corresponding toa command to play back the selected media content. In response toreceiving the input corresponding to the command to play back theselected media content, the control device 130 a transmits a message 651b to the playback device 110 a causing the playback device 110 a to playback the selected media content. In response to receiving the message651 b, the playback device 110 a transmits a message 651 c to the firstcomputing device 106 a requesting the selected media content. The firstcomputing device 106 a, in response to receiving the message 651 c,transmits a message 651 d comprising data (e.g., audio data, video data,a URL, a URI) corresponding to the requested media content.

At step 650 d, the playback device 110 a receives the message 651 d withthe data corresponding to the requested media content and plays back theassociated media content.

At step 650 e, the playback device 110 a optionally causes one or moreother devices to play back the selected media content. In one example,the playback device 110 a is one of a bonded zone of two or more players(FIG. 1M). The playback device 110 a can receive the selected mediacontent and transmit all or a portion of the media content to otherdevices in the bonded zone. In another example, the playback device 110a is a coordinator of a group and is configured to transmit and receivetiming information from one or more other devices in the group. Theother one or more devices in the group can receive the selected mediacontent from the first computing device 106 a, and begin playback of theselected media content in response to a message from the playback device110 a such that all of the devices in the group play back the selectedmedia content in synchrony.

IV. Overview of Example Embodiments

As summarized above, playback groups comprising portable,battery-powered playback devices that can transmit and receive audiocontent among themselves and also receive audio content from an audiosource without a need for a WiFi LAN infrastructure are desirable for atleast the reasons that (i) operating without requiring a WiFi LANinfrastructure requires less networking hardware than embodiments thatrequire a WiFi LAN infrastructure, and allows listeners to enjoy groupplayback in situations where a WiFi LAN infrastructure may not beavailable, and (ii) group members can be repositioned quickly and easilyin a listening environment to accommodate the preferences and/orlocations of listeners.

In some embodiments, a playback group includes a group coordinator andone or more group members, where the group coordinator and the groupmembers are playback devices. In some embodiments, the group coordinatoris or comprises a laptop computer, tablet computer, smartphone or othercomputing device, and the group members are playback devices, such asany of the playback devices disclosed herein.

In some embodiments, the group coordinator, in addition to performingother features and functions, (i) obtains audio content for playback viaa first wireless transmission scheme between a local audio source (e.g.,a smartphone) and the group coordinator and (ii) distributes theobtained audio content to the group members via a second wirelesstransmission scheme. For example, in some embodiments, the audio sourcetransmits packets comprising audio content to the group coordinator viaan Advanced Audio Distribution Profile (A2DP) Bluetooth link or anyother transmission scheme or format now known or later developed that issuitable for transmitting packets of audio content. And in someembodiments, the group coordinator distributes the audio content to thegroup members via Connectionless Slave Broadcast (CSB) Bluetoothtransmission or any other transmission scheme or format now known orlater developed that is suitable to distributing audio content tomultiple playback devices.

In some embodiments, the group coordinator additionally generates andtransmits to the group members both (i) clock timing and (ii) playbacktiming for the audio content. In such embodiments, the group members usethe clock timing and the playback timing to play audio in synchrony witheach other. In embodiments where the group coordinator is configured toplay audio in synchrony with the group members, the group coordinatorand the group members all use the clock timing and playback timing toplay the audio in synchrony with each other.

In some embodiments, the group coordinator may transmit the clock timingand/or the playback timing to the group members via CSB transmission orother suitable broadcast or multicast transmission. In some embodiments,the group coordinator may transmit the clock timing and/or the playbacktiming to the group members via one or more separate transmissions,which may be unicast, multicast, or broadcast. In some embodiments, theseparate transmission may include a Bluetooth, Bluetooth Low Energy(BLE), or other type of transmission now know or later developed that issuitable for conveying signaling information.

In some embodiments, however, clock timing or some other common clockreference may be generated and provided by a device other than the groupcoordinator. For example, in some embodiments, the clock timinginformation may be provided by another group member or perhaps anotherdevice that is separate from the playback group.

V. Technical Features

In some embodiments, at least some aspects of the technical solutionsderive from the technical structure and organization of the audiocontent, the playback timing, and clock timing information that theplayback devices use to play audio content from audio sources insynchrony with each other or in some other groupwise fashion, includinghow playback devices generate playback timing based on clock timing andplay audio content based on playback timing and clock timing.

Therefore, to aid in understanding certain aspects of the disclosedtechnical solutions, certain technical details of the audio content,playback timing, and clock timing information, as well as how playbackdevices generate and/or use playback timing and clock timing for playingaudio content are described below. Except where noted, the technicaldetails of the audio content, playback timing, and clock timinginformation described below are the same or at least substantially thesame for the examples shown and described herein with reference to FIGS.7 and 8.

a. Audio Content

Audio content may be any type of audio content now known or laterdeveloped. For example, in some embodiments, the audio content includesany one or more of: (i) streaming music or other audio obtained from astreaming media service, such as Spotify, Pandora, or other streamingmedia services; (ii) streaming music or other audio from a local musiclibrary, such as a music library stored on a user's laptop computer,desktop computer, smartphone, tablet, home server, or other computingdevice now known or later developed; (iii) audio content associated withvideo content, such as audio associated with a television program ormovie received from any of a television, set-top box, Digital VideoRecorder, Digital Video Disc player, streaming video service, or anyother source of audio-visual media content now known or later developed;(iv) text-to-speech or other audible content from a voice assistantservice (VAS), such as Amazon Alexa or other VAS services now known orlater developed; (v) audio content from a doorbell or intercom systemsuch as Nest, Ring, or other doorbells or intercom systems now known orlater developed; and/or (vi) audio content from a telephone, videophone, video/teleconferencing system or other application configured toallow users to communicate with each other via audio and/or video.

In some embodiments, a group coordinator (sometimes referred to as a“sourcing” device) obtains any of the aforementioned types of audiocontent from an audio source via an interface on the group coordinator,e.g., one of the group coordinator's network interfaces, a “line-in”analog interface, a digital audio interface, or any other interfacesuitable for receiving audio content in digital or analog format nowknown or later developed.

An audio source is any system, device, or application that generates,provides, or otherwise makes available any of the aforementioned audiocontent to a group coordinator or playback device. Examples of audiosources include streaming media (audio, video) services, digital mediaservers or other computing systems, voice assistant services (VAS),televisions, cable set-top-boxes, streaming media players (e.g.,AppleTV, Roku, gaming console), CD/DVD players, doorbells, intercoms,telephones/smartphones, tablets, or any other source of audio contentnow known or later developed.

As mentioned earlier, a playback device that receives or otherwiseobtains audio content from an audio source for playback and/ordistribution to other playback devices in a playback group is sometimesreferred to herein as the group coordinator or “sourcing” device for theplayback group.

One function of the group coordinator of a playback group in someembodiments is to process received audio content for playback and/ordistribution to group members of the playback group for groupwiseplayback. In some embodiments, the group coordinator transmits theprocessed audio content to all the other group members in the playbackgroup. In some embodiments, the group coordinator transmits the audiocontent to a multicast network address, and all the group memberplayback devices configured to play the audio content (i.e., the groupmembers of the playback group) receive the audio content via thatmulticast address. In some embodiments, the group coordinator broadcaststhe audio content on a wireless channel and the group members in theplayback group receive the broadcast. For example, in some embodiments,the group coordinator transmits the audio content to the group membersvia Connectionless Slave Broadcast (CSB) Bluetooth transmission.

In some embodiments, the group coordinator receives audio content froman audio source in digital form, e.g., via a stream of packets. In someembodiments, individual packets in the stream have a sequence number orother identifier that specifies an ordering of the packets. Inoperation, the group coordinator uses the sequence number or otheridentifier to detect missing packets and/or to reassemble the packets ofthe stream in the correct order before performing further processing. Insome embodiments, the sequence number or other identifier that specifiesthe ordering of the packets is or at least comprises a timestampindicating a time when the packet was created. The packet creation timecan be used as a sequence number based on an assumption that packets arecreated in the order in which they should be subsequently played out.For example, in some embodiments, the group coordinator receives audiocontent from an audio source via an Advanced Audio Distribution Profile(A2DP) Bluetooth link.

In some embodiments, individual packets from an audio source may includeboth a timestamp and a sequence number. The timestamp is used to placethe incoming packets of audio content in the correct order, and thesequence number is mainly used to detect packet losses. In operation,the sequence numbers increase by one for each Real-time TransportProtocol (RTP) packet transmitted from the audio source, and timestampsincrease by the time “covered” by an RTP packet. In instances where aportion of audio content is split across multiple RTP packets, multipleRTP packets may have the same timestamp.

In some embodiments, the group coordinator does not change the sequencenumber or identifier (or timestamp, if applicable) of a received packetduring processing. But in some embodiments, the group coordinator mayreorder at least a first set of packets in a packet stream received froman audio source (an inbound stream) based on each packet's sequenceidentifier, extract audio content from the received packets, reassemblea bitstream of audio content from the received packets, and thenrepacketize the reassembled bitstream into an outbound set of packets(an outbound stream), where packets in the outbound stream have sequencenumbers and/or timestamps that differ from the sequence numbers and/ortimestamps of the packets in the first set of packets (or first stream).

In some embodiments, individual packets in the outbound stream may be adifferent length (i.e., shorter or longer) than individual packets inthe inbound stream. In some embodiments, reassembling a bitstream fromthe incoming packet stream and then subsequently repacketizing thereassembled bitstream into a different set of packets facilitatesuniform processing and/or transmission of audio content by the groupcoordinator and uniform processing by the group members that receive theaudio content from the group coordinator.

However, for some delay-sensitive audio content, reassembly andrepacketization may be undesirable, and therefore, in some embodiments,the group coordinator may not perform reassembly and repacketization forsome (or all) audio content that it receives before playing the audiocontent and/or transmitting the audio content to other playbackdevices/group members.

b. Playback Timing

In some embodiments, the playback devices disclosed and described hereinuse playback timing to play audio content in synchrony with each other.An individual playback device can generate playback timing and/orplayback audio content according to playback timing, based on theplayback device's configuration in the playback group. The sourcingplayback device (acting as a group coordinator) that generates theplayback timing for audio content also transmits that generated playbacktiming to all the playback devices that are configured to play the audiocontent (the group members).

In some embodiments, the group coordinator transmits playback timingseparately from the audio content. For example, and as described herein,in some embodiments, the group coordinator (i) transmits audio contentto the group members via Connectionless Slave Broadcast (CSB) Bluetoothtransmission and (ii) transmits playback timing for the audio contentvia a Bluetooth or Bluetooth Low Energy (BLE) transmission. In someembodiments, the group coordinator (i) transmits audio content to thegroup members via a first set of CSB transmissions, and (ii) transmitsplayback timing for the audio content to the group members via a secondset of CSB transmissions. As explained herein, in some embodiments, somegroup members may receive audio content by “listening” to A2DPtransmissions from an audio source to the group coordinator. The groupmembers who receive audio content via the A2DP transmissions do not needreceive that same audio content from a later CSB transmission, so thosegroup members need not activate their radios to receive those later CSBtransmissions. But if the group members know that the group coordinatorwill transmit playback timing information for audio content during aregularly scheduled (or semi-regularly scheduled) CSB transmission, thegroup members can activate their radios to receive the groupcoordinator's CSB transmissions comprising the playback timing but notactivate their radios to receive the group coordinator's CSBtransmissions comprising the audio content (unless a particular groupmember failed to receive a portion of audio content in an earlier A2DPtransmission, in which case, that group member could activate its radioto receive later CSB transmissions from the group member to receive themissing (or perhaps corrupted) portion of audio content).

In some embodiments, the group coordinator transmits the playback timingto all the group members by transmitting the playback timing to amulticast network address for the playback group, and all the groupmembers receive the playback timing via the playback group's multicastaddress. In some embodiments, the group coordinator transmits theplayback timing to each group member by transmitting the playback timingto each group member's unicast network address.

In some Bluetooth-based embodiments, the group coordinator transmits theplayback timing to all the group members by transmitting the playbacktiming to a set of group members via one or more of BluetoothConnectionless Slave Broadcast (CSB) transmission, Active SlaveBroadcast (ASB) transmission, LE Advertising Broadcast (ADVB)transmission, LE Periodic Advertising Broadcast (PADVB) transmission, orBroadcast Isochronous Stream (BIS) transmission. In some Bluetooth-basedembodiments, the group coordinator transmits the playback timing to eachgroup member individually via one or more of Bluetooth SynchronousConnection-Oriented (SCO) transmission, Bluetooth Enhanced SynchronousConnection-Oriented (eSCO) transmission, Bluetooth LE Asynchronousconnection (LE ACL) transmission, or Bluetooth Connected IsochronousStream (CIS) transmission.

In some embodiments, the playback timing is generated for individualframes (or packets) of audio content. In some embodiments, the audiocontent is packaged in a series of frames (or packets) where individualframes (or packets) comprise a portion of the audio content. In someembodiments, the playback timing for the audio content includes aplayback time for each frame (or packet) of audio content. In someembodiments, the playback timing for an individual frame (or packet) isincluded within the frame (or packet), e.g., in the header of the frame(or packet), in an extended header of the frame (or packet), and/or inthe payload portion of the frame (or packet). But as described earlier,in some embodiments, the group coordinator transmits playback timing forone or more individual frames separately from the audio content.

In some embodiments, the playback time for an individual frame (orpacket) is identified within a timestamp or other indication. In suchembodiments, the timestamp (or other indication) represents a time toplay the one or more portions of audio content within that individualframe (or packet).

In operation, when the playback timing for an individual frame (orpacket) is generated, the playback timing for that individual frame (orpacket) is a future time relative to a current clock time of a referenceclock at the time that the playback timing for that individual frame (orpacket) is generated. As described in more detail below, the referenceclock can be a “local” clock at the group coordinator or a “remote”clock at a separate network device, e.g., another playback device, acomputing device, or another network device configured to provide clocktiming for use by playback devices to generate playback timing and/orplayback audio content.

In operation, a playback device tasked with playing particular audiocontent will play the portion(s) of the particular audio content withinan individual frame (or packet) at the playback time specified by theplayback timing for that individual frame (or packet), as adjusted toaccommodate for differences between the clock timing information and aclock at the playback device that is tasked with playing the audiocontent, as describe in more detail below.

c. Clock Timing

The playback devices disclosed and described herein use clock timing togenerate playback timing for audio content and to play the audio contentbased on the audio content and the generated playback timing.

In some embodiments, the group coordinator uses clock timing from areference clock (e.g., a device clock, a digital-to-audio converterclock, a playback time reference clock, or any other clock) to generateplayback timing for audio content that the group coordinator receivesfrom an audio source. The reference clock can be a “local” clock at thegroup coordinator or a “remote” clock at a separate network device,e.g., another playback device, a computing device, or another networkdevice configured to provide clock timing for use by (i) a groupcoordinator to generate playback timing and/or (ii) the groupcoordinator and group members to play back audio content.

In some embodiments, all of the playback devices tasked with playingparticular audio content in synchrony (i.e., all the group members in aplayback group) use the same clock timing from the same reference clockto play back that particular audio content in synchrony with each other.In some embodiments, playback devices use the same clock timing to playaudio content that was used to generate the playback timing for theaudio content. The reference clock may be a local clock of the groupcoordinator, but the reference clock could also be a clock at adifferent device, including a different playback device.

In operation, the device that generates the clock timing also transmitsthe clock timing to all the playback devices in the network that need touse the clock timing for generating playback timing and/or playing backaudio content. In some embodiments, the device that generates the clocktiming (e.g., the group coordinator in some embodiments) transmits theclock timing to a multicast network address, and all the playbackdevices configured to generate playback timing and/or play audio content(e.g., the group coordinator and/or the group members) receive the clocktiming via that multicast address. In some embodiments, the device thatgenerates the clock timing alternatively transmits the clock timing toeach unicast network address of each playback device in the playbackgroup.

In some embodiments, the device that generates the clock timing is aplayback device configured to operate as the group coordinator for theplayback group. And in operation, the group coordinator of the playbackgroup transmits the clock timing to all the group members of theplayback group. In some embodiments, the group coordinator transmitsclock timing to group members via one or more CSB transmissions,Bluetooth Classic (i.e., Bluetooth Basic Rate/Extended Data Rate(BR/EDR)) or Bluetooth Low Energy (BLE) transmissions (e.g., BLE LEAdvertising Broadcast (ADVB), LE Periodic Advertising Broadcast (PADVB),and Broadcast Isochronous Stream (BIS)), or via any other transmissionsor transmission schemes suitable for transmitting clock timinginformation now known or later developed. In some embodiments, the groupcoordinator transmits instructions to the group members directing themto use or synchronize to a reference clock derived or received from anindependent but reliable source (such as GPS or cellular network). Andin some embodiments, the group coordinator and the group members all usethe clock timing and the playback timing to play audio content in agroupwise manner. In some embodiments, the group coordinator and thegroup members all use the clock timing and the playback timing to playaudio content in synchrony with each other.

d. Generating Playback Timing by the Group Coordinator

In some embodiments, the group coordinator: (i) generates playbacktiming for audio content based on clock timing from a local clock at thegroup coordinator, and (ii) transmits the generated playback timing toall the other group members in the playback group. In operation, whengenerating playback timing for an individual frame (or packet), thegroup coordinator adds a “timing advance” to the current clock time of alocal clock at the group coordinator that the group coordinator is usingfor generating the playback timing.

In some embodiments, the “timing advance” is based on an amount of timethat is greater than or equal to the sum of (i) the network transit timerequired for frames and/or packets comprising audio content transmittedfrom the group coordinator to arrive at all the other group members and(ii) the amount of time required for all the other group members toprocess received frames/packets from the group coordinator for playback.

In some embodiments, the group coordinator determines a timing advanceby sending one or more test packets to one or more (or perhaps all) ofthe other group members, and then receiving test response packets backfrom those one or more group members. In some embodiments, the groupcoordinator and the one or more group members negotiate a timing advancevia multiple test and response messages. In some embodiments with morethan two group members, the group coordinator determines a timingadvance by exchanging test and response messages with all of the groupmembers, and then setting a timing advance that is sufficient for thegroup member having the longest total of network transmit time andpacket processing time.

In some embodiments, the timing advance is less than about 50milliseconds. In some embodiments, the timing advance is less than about20-30 milliseconds. And in still further embodiments, the timing advanceis less than about 10 milliseconds. In some embodiments, the timingadvance remains constant after being determined, or at least constantfor the duration of a synchronous playback session. In otherembodiments, the group coordinator can change the timing advance inresponse to a request from a group member indicating that a greatertiming advance is required (e.g., because the group member is notreceiving packets comprising portions of audio content until after oneor more other group members have already played the portions of audiocontent) or a shorter timing advance would be sufficient (e.g., becausethe group member is buffering more packets comprising portions of audiocontent than necessary to provide consistent, reliable playback).

As described in more detail below, all the playback devices in aplayback group configured to play the audio content in synchrony willuse the playback timing and the clock timing to play the audio contentin synchrony with each other.

e. Generating Playback Timing with Clock Timing from a Remote Clock

In some embodiments, the group coordinator may generate playback timingfor audio content based on clock timing from a remote clock at anothernetwork device, e.g., another playback device, another computing device(e.g., a smartphone, laptop, media server, or other computing deviceconfigurable to provide clock timing sufficient for use by the groupcoordinator generate playback timing and/or playback audio content).Generating playback timing based on clock timing from a remote clock atanother network device is more complicated than generating playbacktiming based on clock timing from a local clock in embodiments where thesame clock timing is used for both (i) generating playback timing and(ii) playing audio content based on the playback timing.

In embodiments where the group coordinator generates playback timing foraudio content based on clock timing from a remote cock, the playbacktiming for an individual frame (or packet) is based on (i) a “timingoffset” between (a) a local clock at the group coordinator that thegroup coordinator uses for generating the playback timing and (b) theclock timing information from the remote reference clock, and (ii) a“timing advance” based on an amount of time that is greater than orequal to the sum of (a) the network transit time required for packetstransmitted from the group coordinator to arrive at the group membersand (b) the amount of time required for all of those group members toprocess frames and/or packets comprising audio content received from thegroup coordinator for playback.

For an individual frame (or packet) containing a portion(s) of the audiocontent, the group coordinator generates playback timing for thatindividual frame (or packet) by adding the sum of the “timing offset”and the “timing advance” to a current time of the local clock at thegroup coordinator that the group coordinator uses to generate theplayback timing for the audio content. In operation, the “timing offset”may be a positive or a negative offset, depending on whether the localclock at the group coordinator is ahead of or behind the remote clockproviding the clock timing. The “timing advance” is a positive numberbecause it represents a future time relative to the local clock time, asadjusted by the “timing offset.”

By adding the sum of the “timing advance” and the “timing offset” to acurrent time of the local clock at the group coordinator that the groupcoordinator is using to generate the playback timing for the audiocontent, the group coordinator is, in effect, generating the playbacktiming relative to the remote clock.

In some embodiments, and as described above, the “timing advance” isbased on an amount of time that is greater than or equal to the sum of(i) the network transit time required for frames and/or packetscomprising audio content transmitted from the group coordinator toarrive at all other group members and (ii) the amount of time requiredfor all the other group members to process received frames/packets fromthe sourcing playback device for playback.

In some embodiments, the group coordinator determines a timing advancevia signaling between the group coordinator and one or more groupmembers, as described previously. Further, in some embodiments, thetiming advance is less than about 50 milliseconds, less than about 20-30milliseconds, or less than about 10 milliseconds, depending on the audiocontent playback latency requirements because different audio contentmay have different latency requirements. For example, audio contenthaving associated video content may have lower latency requirements thanaudio content that does not have associated video content because audiocontent associating with video content must be synchronized with itscorresponding video content whereas audio content that is not associatedwith video content need not be synchronized with any corresponding videocontent. In some embodiments, the timing advance remains constant afterbeing determined, or at least constant for the duration of a playbacksession. And in some embodiments, the group coordinator can change thetiming advance based on further signaling between the group coordinator(generating the playback timing) and one or more group members (that areusing the playback timing to play audio content).

As described in more detail below, all the playback devices configuredto play the audio content in synchrony will use the playback timing andthe clock timing to play the audio content in synchrony with each other.

f. Playing Audio Content Using Local Playback Timing and Local ClockTiming

In some embodiments, the group coordinator is configured to play audiocontent in synchrony with one or more group members. And if the groupcoordinator is using clock timing from a local clock at the groupcoordinator to generate the playback timing, then the group coordinatorwill play the audio content using locally-generated playback timing andthe locally-generated clock timing. In operation, the group coordinatorplays an individual frame (or packet) comprising portions of the audiocontent when the local clock that the group coordinator used to generatethe playback timing reaches the time specified in the playback timingfor that individual frame (or packet).

For example, recall that when generating playback timing for anindividual frame (or packet), the group coordinator device adds a“timing advance” to the current clock time of the reference clock usedfor generating the playback timing. In this instance, the referenceclock used for generating the playback timing is a local clock at thegroup coordinator. So, if the timing advance for an individual frame is,for example, 30 milliseconds, then the group coordinator plays theportion (e.g., a sample or set of samples) of audio content in anindividual frame (or packet) 30 milliseconds after creating the playbacktiming for that individual frame (or packet).

In this manner, the group coordinator plays audio content by usinglocally-generated playback timing and clock timing from a localreference clock at the group coordinator. By playing the portion(s) ofthe audio content of an individual frame and/or packet when the clocktime of the local reference clock reaches the playback timing for thatindividual frame or packet, the group coordinator plays that portion(s)of the audio content in that individual frame and/or packet in synchronywith other group members in the playback group.

g. Playing Audio Content Using Local Playback Timing and Remote ClockTiming

As mentioned earlier, in some embodiments, a group coordinator generatesplayback timing for audio content based on clock timing from a remoteclock, i.e., a clock at another network device separate from the groupcoordinator, e.g., another playback device, or another computing device(e.g., a smartphone, laptop, media server, or other computing deviceconfigurable to provide clock timing sufficient for use by a playbackdevice generate playback timing and/or playback audio content). Becausethe group coordinator used clock timing from the remote clock togenerate the playback timing for the audio content, the groupcoordinator also uses the clock timing from the remote clock to play theaudio content. In this manner, the group coordinator plays audio contentusing the locally-generated playback timing and the clock timing fromthe remote clock.

Recall that, in embodiments where the group coordinator generatesplayback timing for audio content based on clock timing from a remoteclock, the group coordinator generates the playback timing for anindividual frame (or packet) based on (i) a “timing offset” based on adifference between (a) a local clock at the group coordinator and (b)the clock timing information from the remote clock, and (ii) a “timingadvance” comprising an amount of time that is greater than or equal tothe sum of (a) the network transit time required for frames/packetstransmitted from the group coordinator to arrive at all the groupmembers and (b) the amount of time required for all of the group membersto process frames and/or packets comprising audio content received fromthe group coordinator for playback. And further recall that the groupcoordinator transmits the generated playback timing to all of the groupmembers in the playback group tasked with playing the audio content insynchrony.

In this scenario, to play an individual frame (or packet) of audiocontent in synchrony with the one or more other group member playbackdevices, the group coordinator subtracts the “timing offset” from theplayback timing for that individual frame (or packet) to generate a“local” playback time for playing the audio content based on the audiocontent within that individual frame (or packet). After generating the“local” playback time for playing the portion(s) of the audio contentwithin the individual frame (or packet), the group coordinator plays theportion(s) of the audio content in the individual frame (or packet) whenthe local clock that the group coordinator is using to play the audiocontent reaches the “local” playback time for that individual frame (orpacket). By subtracting the “timing offset” from the playback timing togenerate the “local” playback time for an individual frame, the groupcoordinator effectively plays the portion(s) of audio content in thatframe/packet with reference to the clock timing from the remote clock.

h. Playing Audio Content Using Remote Playback Timing and Local ClockTiming

Recall that, in some embodiments, the group coordinator transmits theaudio content and the playback timing for the audio content to one ormore group members. If the group member that receives (i.e., thereceiving group member) the audio content and playback timing from thegroup coordinator is the same group member that provided clock timinginformation to the group coordinator that the group coordinator used forgenerating the playback timing, then the receiving group member in thisinstance plays audio content using the playback timing received from thegroup coordinator (i.e., remote playback timing) and the group member'sown clock timing (i.e., local clock timing). Because the groupcoordinator used clock timing from a clock at the receiving group memberto generate the playback timing, the receiving group member also usesthe clock timing from its local clock to play the audio content. In thismanner, the receiving group member plays audio content using the remoteplayback timing (i.e., from the group coordinator) and the clock timingfrom its local clock (i.e., its local clock timing).

To play an individual frame (or packet) of the audio content insynchrony with the group coordinator (and every other playback devicethat receives the playback timing from the group coordinator and clocktiming from the receiving group member), the receiving group member (i)receives the frames (or packets) comprising the portions of the audiocontent from the group coordinator, (ii) receives the playback timingfor the audio content from the group coordinator (e.g., in the frameand/or packet headers of the frames and/or packets comprising theportions of the audio content or perhaps separately from the framesand/or packets comprising the portions of the audio content), and (iii)plays the portion(s) of the audio content in the individual frame (orpacket) when the local clock that the receiving group member used togenerate the clock timing reaches the playback time specified in theplayback timing for that individual frame (or packet) received from thegroup coordinator.

Because the group coordinator uses the “timing offset” (which is thedifference between the clock timing at the receiving group member andthe clock timing at the group coordinator in this scenario) whengenerating the playback timing, and because this “timing offset” alreadyaccounts for differences between timing at the group coordinator and thereceiving group member, the receiving group member in this scenarioplays individual frames (or packets) comprising portions of the audiocontent when the receiving group member's local clock (that was used togenerated the clock timing) reaches the playback time for an individualframe (or packet) specified in the playback timing for that individualframe (or packet).

And because the receiving group member plays frames (or packets)comprising portions of the audio content according to the playbacktiming, and because the group coordinator plays the same frames (orpackets) comprising portions of the audio content according to theplayback timing and the determined “timing offset,” the receiving groupmember and the group coordinator play the same frames (or packets)comprising audio content in synchrony, i.e., at the same time or atsubstantially the same time.

i. Playing Audio Content Using Remote Playback Timing and Remote ClockTiming

Recall that, in some embodiments, the sourcing playback device (e.g.,which in many cases may be the group coordinator) transmits the audiocontent and the playback timing for the audio content to one or moreother playback devices in the synchrony group. And further recall that,in some embodiments, the network device providing the clock timing canbe a different device than the playback device providing the audiocontent and playback timing (i.e., the sourcing playback device, whichin many cases may be the group coordinator). Playback devices thatreceive the audio content, the playback timing, and the clock timingfrom one or more other devices are configured to playback the audiocontent using the playback timing from the device that provided theplayback timing (i.e., remote playback timing) and clock timing from aclock at the device that provided the clock timing (i.e., remote clocktiming). In this manner, the receiving group member playback device inthis instance plays audio content by using remote playback timing andremote clock timing.

To play an individual frame (or packet) of the audio content insynchrony with every other playback device tasked with playing audiocontent in the playback group, the receiving playback device (i)receives the frames (or packets) comprising the portions of the audiocontent, (ii) receives the playback timing for the audio content (e.g.,in the frame and/or packet headers of the frames and/or packetscomprising the portions of the audio content or perhaps separately fromthe frames and/or packets comprising the portions of the audio content),(iii) receives the clock timing, and (iv) plays the portion(s) of theaudio content in the individual frame (or packet) when the local clockthat the receiving playback device uses for audio content playbackreaches the playback time specified in the playback timing for thatindividual frame (or packet), as adjusted by a “timing offset.”

In operation, after the receiving playback device receives clock timing,the receiving device determines a “timing offset” for the receivingplayback device. This “timing offset” comprises (or at least correspondsto) a difference between the “reference” clock that was used to generatethe clock timing and a “local” clock at the receiving playback devicethat the receiving playback device uses to play the audio content. Inoperation, each playback device that receives the clock timing fromanother device calculates its own “timing offset” based on thedifference between its local clock and the clock timing, and thus, the“timing offset” that each playback device determines is specific to thatparticular playback device.

In some embodiments, when playing back the audio content, the receivingplayback device generates new playback timing (specific to the receivingplayback device) for individual frames (or packets) of audio content byadding the previously determined “timing offset” to the playback timingfor each received frame (or packet) comprising portions of audiocontent. With this approach, the receiving playback device converts theplayback timing for the received audio content into “local” playbacktiming for the receiving playback device. Because each receivingplayback device calculates its own “timing offset,” each receivingplayback device's determined “local” playback timing for an individualframe is specific to that particular playback device.

And when the “local” clock that the receiving playback device is usingfor playing back the audio content reaches the “local” playback time foran individual frame (or packet), the receiving playback device plays theaudio content (or portions thereof) associated with that individualframe (or packet). As described above, in some embodiments, the playbacktiming for a particular frame (or packet) is in the header of the frame(or packet). In other embodiments, the playback timing for individualframes (or packets) is transmitted separately from the frames (orpackets) comprising the audio content.

Because the receiving playback device plays frames (or packets)comprising portions of the audio content according to the playbacktiming as adjusted by the “timing offset” relative to the clock timing,and because the device providing the playback timing generated theplayback timing for those frames (or packets) relative to the clocktiming and plays the same frames (or packets) comprising portions of theaudio content according to the playback timing and its determined“timing offset,” the receiving playback device and the device thatprovided the playback timing (e.g., the group coordinator in someembodiments) play the same frames (or packets) comprising the sameportions of the audio content in synchrony with each other, i.e., at thesame time or at substantially the same time.

VI. Example Embodiments

FIG. 7 shows an example configuration 700 of a media playback systemconfigured for hybrid sniffing and rebroadcast in a network according tosome embodiments. Although configure 700 shows a Bluetooth network as anexample, the features and functions described herein are equallyapplicable to other networking protocols, too, including but not limitedto network protocols for peer-to-peer, mesh, infrastructure, and/orad-hoc networks.

The media playback system 700 in FIG. 7 includes playback devices 704,710, 712, and 714. Playback device 704 is configured as a groupcoordinator (GC) and playback devices 710, 712, and 714 are configuredas group members (GM). The playback devices 704, 710, 712, and 714 maybe the same as or similar to any of the playback devices disclosed anddescribed herein. In some embodiments, one or more of the playbackdevices 704, 710, 712, and 714 are portable, battery-powered wirelessplayback devices.

In the example shown in FIG. 7, the audio source 702 is a mobile audiosource, such as a smartphone, tablet, or other mobile audio source. Theaudio source 702 transmits packets of audio content to the groupcoordinator 704. In example system 700, the audio source 702 transmitspackets of audio content via an Advanced Audio Distribution Profile(A2DP) Bluetooth link 720. However, in some embodiments, the audiosource 702 may transmit the audio content to the group coordinator 704via another suitable communication link instead. The audio content maybe any of the various types of audio content disclosed herein. In someembodiments, the audio content is in the form of streaming audio contentfrom the audio source 702.

The group coordinator 704 (i) receives the audio content via theAdvanced Audio Distribution Profile (A2DP) Bluetooth link 720 betweenthe audio source 702 and the group coordinator 704 and (ii) distributesthe obtained audio content to the group members 710, 712, and 714 viaConnectionless Slave Broadcast (CSB) Bluetooth transmission to the groupmembers 710, 712, and 714. That is, the audio content that the groupcoordinator 704 distributes to the group members 710, 712, and 714 isthe same audio content that the group coordinator 704 obtains from theaudio source 702. However, in some embodiments, the audio content may bepackaged in differently-sized and/or differently-formatted packets orframes for the A2DP transmissions as compared to the CSB broadcasts.

In operation, the group coordinator 704 is configured to communicatewith the audio source 702 via the A2DP link 720 during a first set oftransmission time intervals (i.e., A2DP transmission time intervals) andconfigured to communicate with the group members 710, 712, and 714 viathe CSB transmissions 730, 732, and 734 during a second set oftransmission time intervals (i.e., CSB transmission time intervals). Insome embodiments, individual A2DP transmission time intervals in the setof A2DP transmission time intervals do not overlap in time withindividual CSB transmission time intervals in the set of CSBtransmission time intervals. In operation, the A2DP and CSB transmissiontime intervals comprise alternating transmit time intervals, e.g., oneor more A2DP transmit time intervals, followed by one or more CSBtransmit time intervals, followed by one or more A2DP transmit timeintervals, followed by one or more CSB transmit time intervals, and soon. In some embodiments, each alternate time interval is on the order ofa few milliseconds to tens of milliseconds.

In some embodiments, the group coordinator includes a Bluetoothsubsystem comprising a Baseband Resource Manager component (a physicalor virtual component) that implements a scheduler configured tocoordinate transmission times. In some embodiments, one or more of thegroup coordinator, group member(s), and/or audio source may use theBluetooth Slot Availability Mask (SAM) feature, which allows a firstdevice to inform a second device about times when the first device willnot be able to communicate. In such embodiments, the group coordinatorcan use the SAM feature to inform the audio source of transmission timeintervals (or similar transmission timeframes) that the groupcoordinator needs to reserve (or has reserved) for sending clock timing,audio content, and/or playback timing for audio content to groupmembers. In some embodiments using the SAM feature, the audio source(individually or in combination with the group coordinator) can scheduleits A2DP transmissions with the group coordinator so that the A2DPtransmissions are not transmitted during the same transmission timeintervals as the group coordinator's CSB transmissions (or BluetoothClassic, BLE or other group coordinator to group member transmissions,depending on the implementation).

For illustration purposes, FIG. 7 shows the group coordinator 704transmitting the audio content to the group members 710, 712, and 714via separate CSB transmissions 730, 732, and 734, respectively. However,for CSB transmission, in practice, group coordinator 704 broadcasts theaudio content via CSB transmissions that are received by each of thegroup members 710, 712, and 714 rather than separate CSB transmissionsto each of the group members 710, 712, and 714. In some embodiments, thegroup coordinator 704 may distribute the audio content to the groupmembers 710, 712, and 714 via one or more other and/or alternativetransmission links suitable for distributing audio content to playbackdevices, including but not limited to, for example, Active SlaveBroadcast (ASB), Bluetooth Low Energy (BLE), Infrastructure-based WiFi,ad-hoc WiFi, or Ultra-wideband (UWB).

Group coordinator 704 is also configured to transmit signaling and/orcontrol information to individual group members 710, 712, and 714. Inoperation, the signaling and/or control information includes, but is notlimited to, one or more of (i) playback timing information and clocktiming information that the group members 710, 712, and 714 use to playthe audio content in synchrony with the other playback devices in theplayback group or (ii) other signaling information that the groupmembers 710, 712, and 714 use to manage the setup and operation of theplayback group, e.g., signaling for establishing which playback deviceshould be the group coordinator, signaling for transferring the groupcoordinator responsibility from one playback device to another playbackdevice, volume control for the playback devices in the playback group,playback control (e.g., start, stop, or pause playback), and/orsignaling used to add new playback devices (not shown) to the playbackgroup or drop any of the playback devices from the playback group.

The group coordinator 704 may transmit other signaling and/or controlinformation to the group members 710, 712, and 714, too. For example,other signaling and/or control information includes, but is not limitedto: (i) information about the A2DP link (or channel) between the groupcoordinator and the audio source and (ii) information about the CSB link(or channel) between the group coordinator and the group members. For anindividual link (or channel), the communication configurationinformation may include one or more of (i) a channel or link identifier,(ii) a frequency hopping sequence for the channel or link, (iii) asecurity key to decode transmissions, and/or (iv) other channel or linkparameters that may be required or desired for the group member totransmit and/or receive data via the channel/link.

In some embodiments, at least some of the above-described signalingand/or control information may be transmitted from the group coordinator704 to the group members 710, 712, and 714 via the CSB transmissions.For example, in some embodiments, the group coordinator 704 may transmitplayback timing and/or clock timing to the group members 710, 712, and714 via the CSB transmissions.

In other embodiments, at least some of the above-described signalingand/or control information may be transmitted from the group coordinator704 to the group members 710, 712, and 714 via a signaling channel thatis separate from the CSB transmissions. For example, in someembodiments, the group coordinator 704 may transmit at least some of thesignaling and/or control information to the group members 710, 712, and714 via Bluetooth Classic and/or Bluetooth Low Energy (BLE) transmissionchannels 750, 752, and 754, respectively. For example, in someembodiments, the group coordinator 704 may transmit playback timingand/or clock timing to the group members 710, 712, and 714 via theBluetooth Classic and/or BLE transmission channels 750, 752, and 754,respectively.

In still further embodiments, the group coordinator 704 may inform orinstruct the group members to use clock timing from a remote source,such as a Global Positioning System (GPS), cellular, or Ultra-Wide Band(UWB) signal comprising clock timing information. In such embodiments,the group coordinator and the group members all use the same clocktiming information from the same source. In such embodiments, the groupcoordinator and group members treat the clock timing information fromthe GPS, cellular, or UWB signal as remote clock timing, as describedearlier.

Additionally, because CSB provides for only unidirectional transmissionfrom the group coordinator 704 to the group members 710, 712, and 714,the group members 710, 712, and 714 may also transmit signaling and/orcontrol information back to the group coordinator 704 via the Bluetoothand/or BLE links 750, 752, and 754. For example, in operation, if anindividual group member fails to receive a packet of audio content fromthe group coordinator 704 or receives an errored packet that it isunable to correct, that individual group member may send a retransmitrequest to the group coordinator 704 asking the group coordinator 704 toresend the missing or errored packet. In response, the group coordinator704 may retransmit the missing or errored packet to all the groupmembers via a CSB transmission. Alternatively, the group coordinator 704may transmit the missing or errored packet only to the individual groupmember that sent the retransmit request, e.g., via a direct Bluetooth orBLE link between the group coordinator 704 and that individual groupmember.

In still further embodiments, some of the above-described signalingand/or control information may be transmitted from the group coordinator704 to the group members 710, 712, and 714 via the CSB transmissions,and some of the above-described signaling and/or control information maybe transmitted from the group coordinator 704 to the group members 710,712, and 714 via one or more separate signaling channels, e.g., BLEchannels 750, 752, and 754.

In some embodiments, the group coordinator 704 may transmit at leastsome of the signaling and/or control information via both the CSBchannel and the BLE channels. And in operation, the group members 710,712, and 714 may receive at least some signaling and/or controlinformation via either (or both) of the CSB channel and the BLEchannels.

For example, in the embodiment shown in FIG. 7, the group coordinator704 transmits audio content to the group members 710, 712, and 714 via abroadcast CSB transmission, and the group coordinator 704 transmitsclock timing information and playback timing for the audio content tothe group members 710, 712, and 714 via BLE transmission links 750, 752,and 754, respectively. In some embodiments, the group coordinator 704transmits the audio content and the playback timing for the audiocontent to the group members 710, 712, and 714 via the CSB transmission,and the group coordinator 704 transmits the clock timing and a copy ofthe playback timing to the group members 710, 712, and 714 via the BLEtransmission links 750, 752, and 754. In some embodiments, the playbacktiming that the group coordinator 704 transmits to the group members710, 712, and 714 is a subset of the playback timing that groupcoordinator transmits to the group members 710, 712, and 714 for the BLEtransmission links 750, 752, and 754.

In some embodiments, each packet of audio content that the audio source702 transmits to the group coordinator 704 includes a timestamp and/orsequence identifier. Typically, a packet's timestamp corresponds to atime that the packet was created at the audio source 702 or perhaps atime that the packet was transmitted from the audio source 702 to thegroup coordinator 704. And a packet's sequence identifier typicallycorresponds to that packet's sequence number in a stream of packets.

Although neither the timestamp nor sequence identifier specifies aplayback time, the group coordinator 704 in some embodiments can use thetimestamp and/or the sequence identifier to facilitate the distributionof playback timing to the group members 710, 712, and 714.

For example, in some embodiments, the playback timing informationgenerated by the group coordinator 704 for an individual packet of audiocontent includes both (i) the playback time for the packet, which asdescribed earlier, is a future time relative to a current clock time ofa reference clock that is used to generate the playback timing and (ii)the timestamp and/or sequence identifier of that individual packet. Insuch embodiments, each individual packet of audio content that that thegroup coordinator 704 transmits to the group members 710, 712, and 714also includes the timestamp and/or sequence identifier of thatindividual packet. In this manner, each packet's timestamp and/orsequence identifier enables each group member to match each individualpacket with its corresponding playback time.

In such embodiments, because each individual packet of audio contenttransmitted by the audio source 702 via the A2DP link 720 includes atimestamp (and/or a sequence identifier), and because the groupcoordinator 704 distributes each individual packet of audio content viathe CSB transmissions with the same timestamp (and/or sequenceidentifier) received from the audio source 702 (i.e., the groupcoordinator 704 does not remove the timestamp (and/or sequenceidentifier) provided by the audio source 702), each packet of audiocontent that a group member receives will include both (i) audio contentand (ii) a timestamp (and/or sequence identifier) for that audiocontent—regardless of whether the group member receives that audiopacket from the audio source 702 (e.g., by sniffing the A2DPtransmissions 720 from the audio source 702 to the group coordinator704) or from the group coordinator 704 (e.g., via the CSB transmissionsfrom the group coordinator 704 to the group members 710, 710, and 712).

And in embodiments where the playback timing information for a packet ofaudio content includes the playback time for the packet and the packet'stimestamp (and/or sequence identifier), a group member that receives theplayback timing information from the group coordinator 704 can use eachpacket's timestamp (and/or sequence identifier) to match the packet withits playback time—regardless of whether the group member receives theplayback timing information from the group coordinator 704 via the CSBbroadcast or via a separate signaling link (e.g., a separate Bluetoothor BLE link). For example, in some embodiments, the group coordinatorcan transmit playback timing for a set of audio packets in the form of aplayback timing schedule comprising playback times for a set of packets.

As described earlier, the audio source 702 transmits packets of audiocontent via the A2DP Bluetooth link 720. Typically, the A2DPtransmissions from the audio source 702 to the group coordinator 704 areaddressed to the group coordinator 704. But in some embodiments, thesignaling and/or control information that the group coordinator 704transmits to the group members 710, 712, and 714 includes informationthat enables the group members 710, 712, and 714 to also receive anddecode the A2DP packets that the audio source 702 transmits to the groupcoordinator 704. For example, and as mentioned previously, in someembodiments the group coordinator 704 transmits communicationconfiguration information to the group members 710, 712, and 714 thatincludes (i) information about the A2DP link (or channel) between thegroup coordinator 704 and the audio source 702 and (ii) informationabout the CSB link(s) (or channel(s)) between the group coordinator 704and the group members 710, 712, and 714. For an individual link (orchannel), the communication configuration information may include one ormore of (i) a channel or link identifier, (ii) a frequency hoppingsequence for the channel or link, (iii) a security key to decodetransmissions, and/or (iv) other channel or link parameters that may berequired or desired for the group member to transmit and/or receive datavia the channel/link.

Enabling the group members 710, 712, and 714 to also receive and decodethe A2DP packets sent from the audio source 702 and addressed to thegroup coordinator 704 allows each group member 710, 712, 714 toselectively receive either (i) packets comprising audio content receivedvia the A2DP transmissions from the audio source 702 and addressed tothe group coordinator 704 or (ii) packets comprising audio contentreceived via the CSB transmissions from the group coordinator 704.

This scenario may be advantageous in situations where an individualportable, battery-powered group member is positioned in (or repositionedin) a listening area where it receives packets transmitted via the A2DPlink from the audio source 702 to the group coordinator 704 at a higherreceive power and/or higher signal-to-noise ratio than the packetstransmitted by the group coordinator 704 via the CSB transmissions.

For example, if one group member 714 is in wireless reception range ofthe audio source 702, that group member 714 can use the communicationconfiguration information for the A2DP link 720 to “listen” 744 to thetransmissions on the A2DP link 720 during each A2DP transmission timeinterval. Individual transmissions on the A2DP link 720 include packetsof audio content that the audio source 702 transmits to the groupcoordinator 704. If that group member 714 receives an individual packetof audio content via an A2DP transmission from the audio source 702during an A2DP transmission time interval, then that group member 714can save power by choosing to not activate its radio receiver to receivethat same individual packet of audio content via a later CSBtransmission 734 from the group coordinator 704 during a later CSBtransmission time interval. In this manner, the group member 714selectively receives and processes packets received via one of twostreams of packets comprising audio content, e.g., where the firststream comprises the A2DP stream 720 from the audio source 702 to thegroup coordinator 704 and the second stream comprises the CSB stream 734from the group coordinator 704 to the group member 714. But if groupmember 714 fails to receive one or more packets of audio content (orreceived one or more corrupted packets of audio content) by sniffing theA2DP link from the audio source 702 to the group coordinator 704, thegroup member 714 can activate its radio for at least enough future CSBtransmission time intervals to receive the missing or corruptedpacket(s) when the group coordinator 704 transmits those packets ofaudio content to the broadcast group comprising the group members 710,712, and 714. In this manner, the group member 714 determines whether toreceive packets from an A2DP transmission or a CSB transmission on apacket-by-packet basis.

In some embodiments, to selectively receive and/or process packetsreceived via either the A2DP link or the CSB transmissions, the groupmember 714 implements a buffer (e.g., a ring buffer) configured to storepackets comprising audio content, where each individual buffer entrycorresponds to an upcoming local playback time at which the group member714 will play the portion of audio content stored in that buffer entry.When the group member 714 receives a packet comprising a portion ofaudio content via the A2DP link, the group member 714 determines a localplayback time for that portion of audio content and stores that portionof audio content in the buffer at a buffer entry corresponding to theupcoming playback time for that portion of audio content. Someembodiments may include additionally designating that portion of audiocontent as “valid” via a validity flag or similar indication in thebuffer. For each buffer entry (corresponding to an upcoming localplayback time), if the buffer entry contains a portion of audio content(and if that portion is indicated as “valid” for example), then thegroup member 714 can choose (and in some embodiments does choose) to notactivate its radio for the transmission time interval during which thegroup coordinator 704 later transmits a packet (or packets) comprisingthat same portion of audio content. But if the buffer entry is empty (orif the data in the buffer entry is marked “invalid” for some reasons,e.g., the data is corrupt or contains errors), then the group member 714can choose (and in some embodiments does choose) to activate its radiofor the transmission time interval during which the group coordinator704 later transmits a packet(s) comprising that same portion of audiocontent.

In some embodiments, the group member 714 selectively receiving and/orprocessing packets received via one of the two streams of packetscomprising audio content additionally or alternatively includes thegroup member comparing one or more quality metrics for the A2DPtransmissions with one or more corresponding quality metrics for the CSBtransmissions. In operation, the one or more quality metrics include (i)a wireless SNR (Signal-to-Noise Ratio), (ii) a receive power at thefirst playback device, (iii) a BER (Bit Error Rate) or PER (Packet ErrorRate), (iv) a transmission rate, (v) a RSSI (Received Signal StrengthIndication), (vi) SINR (Signal-to-Interference-plus-Noise Ratio), and(vii) a PDR (Packet-Delivery Ratio).

In response to determining that one or more quality metrics for the A2DPtransmissions are better than the corresponding one or more qualitymetrics for the CSB transmissions, the group member 714 selectivelyreceives and/or processes the packets received via the A2DPtransmissions from the audio source 702 and addressed to the groupcoordinator 704 rather than the packets received via the CSBtransmissions from the group coordinator 704 and addressed to the groupmembers 710, 712, and 714.

And in response to determining that one or more quality metrics for theCSB transmissions are better than one or more corresponding qualitymetrics for the A2DP transmissions, the group member 714 selectivelyreceives and processes packets received via the CSB transmissions fromthe group coordinator 704 and addressed to the group members 710, 712,and 714 rather than the packets received via the A2DP transmissions fromthe audio source 702 and addressed to the group coordinator 704.

In some embodiments, the group member 714 selectively processing packetsreceived via one of the two streams of packets additionally oralternatively includes the group member (i) storing data received viathe A2DP transmissions in a first buffer and (ii) storing data receivedvia the CSB transmissions in a second buffer. The group member 714compares the quality of A2DP transmissions with the quality of the CSBtransmissions. And if the wireless signal quality of the A2DPtransmissions is better than the wireless signal quality of the CSBtransmissions, then the group member 714 processes the packets stored inthe first buffer. But if the wireless signal quality of the CSBtransmissions is better than the wireless signal quality of the A2DPtransmissions, then the group member 714 processes the packets stored inthe second buffer. In some embodiments, the group member 714 may switchbetween processing data stored in the first buffer and processing datastored in the second buffer during audio content playback as thewireless signal quality of the first and second streams changes overtime.

In some embodiments, one or more (or all) of the individual groupmembers 710, 712, and 714 inform the group coordinator 704 which streamit is processing. In other words, an individual group member informs thegroup coordinator 704 whether the group member is obtaining the audiocontent for synchronous playback from (i) the packets received via theA2DP transmissions from the audio source 702 and addressed to the groupcoordinator 704 or (ii) from packets received via the CSB transmissionsfrom the group coordinator 704 and addressed to the group members 710,712, and 714.

In some embodiments, the group coordinator 704, individually or incombination with one or more of the group members 710, 712, and/or714—or alternatively, one of the group members, individually or incombination with the group coordinator or one or more of the other groupmembers—may determine that the role of the group coordinator shouldchange from the current group coordinator 704 to one of the groupmembers 710, 712, or 714 one or more reasons.

For example, as described earlier, a group coordinator's functionsinclude: (i) receiving and processing audio content from the audiosource, (ii) generating playback timing for the audio content, (iii)distributing the audio content, playback timing, and clock timing to allthe group members, and (iv) playing audio based on the audio content,playback timing, and clock timing. And a group member's functionsinclude: (i) receiving audio from at least one of the audio source orthe group coordinator, (ii) receiving playback timing and clock timingfrom the group coordinator, and (iii) playing audio based on the audiocontent, playback timing, and clock timing. Because a playback deviceconfigured to perform the group coordinator role performs more computingand data transmission functions than a playback device configured toperform a group member role (e.g., generating playback timing for theaudio content and distributing the audio content, playback timing andclock timing to the group members), a playback device configured toperform the group coordinator role will typically use more power than asimilar (or the same type of) playback device configured to perform agroup member role. For scenarios where the playback devices 704, 710,712, and/or 714 are portable battery-powered playback devices, theplayback device configured to perform the group coordinator role mayconsume battery power at a faster rate than other playback devicesconfigured to perform as group members.

Therefore, the battery power level of the playback device configured toperform the group coordinator role falls below a certain thresholdlevel, the playback device configured as the group coordinator mayexchange control messages (comprising battery level or other powerconsumption-related information) with the playback devices configured asgroup members to determine whether the group coordinator role should betransferred to one of the group members that has a higher battery powerlevel and/or lower power consumption rate. In some embodiments,transitioning the group coordinator role in this manner may allow agroup of battery-powered playback devices to play audio together for alonger period of time as compared to a scenario where the playbackdevice configured as the group coordinator simply exhausted its battery.In this manner, the playback devices can transfer the group coordinatorrole from playback device to playback device so that the burden of thegroup coordinator role is shared among multiple playback devices.

In another example, and as described earlier, the audio source and/orone or more playback devices may be relocated within and/or moved abouta listening area. Moving and/or relocating the audio source and/or oneor more playback devices within a listening area may affect the wirelesstransmission reliability of the system. For example, if moving the audiosource and/or group coordinator results in the playback deviceconfigured as the group coordinator being positioned far from the audiosource and/or certain group members, it may be advantageous totransition the group coordinator function to another playback devicethat is perhaps closer to the audio source and/or more centrally locatedto all the playback devices in the group. In some embodiments, the groupcoordinator exchanges control messages (e.g., comprising wirelessnetwork metrics) with the group members. These control messages mayinclude information about one or more of device-to-device (i) wirelessSNR (Signal-to-Noise Ratio), (ii) receive power, (iii) a BER (Bit ErrorRate) or Packet Error Rate (PER), (iv) a transmission rate, (v) a RSSI(Received Signal Strength Indication), (vi) SINR(Signal-to-Interference-plus-Noise Ratio), and/or (vii) a PDR(Packet-Delivery Ratio).

For example, one or more of the playback devices may measure and/orassess one or more of the listed wireless metrics relative to one ormore other playback devices in the group and/or the audio source toobtain an estimate of the wireless network topology. And based on theestimated wireless network topology, the group coordinator—individuallyor in combination with one or more group members—may decide that anotherplayback device closer to the audio source and/or more centrally locatedwithin the estimated wireless network topology would be better suited toperform the group coordinator role. In this manner, the wirelessreliability of the group as a whole may be improved by transitioning thegroup coordinator role to a playback device closer to the audio sourceand/or more centrally located in the group.

VII. Example Methods

FIG. 8 shows an example method 800 performed by a playback deviceconfigured for hybrid sniffing and rebroadcast in wireless networks,including Bluetooth networks, according to some embodiments. Theplayback device may be the same as or similar to any of the playbackdevices disclosed herein.

Method 800 begins at step 802, which includes the playback deviceselectively receiving and/or processing packets received via one of twostreams of packets comprising media content, wherein a first stream istransmitted from a source device via a first wireless channel andaddressed to a second playback device, and wherein a second stream istransmitted from the second playback device via a second wirelesschannel and addressed to a broadcast group comprising the first playbackdevice.

In some embodiments, the source device is an audio source that is thesame as or similar to any of the audio sources disclosed and describedherein, including but not limited to audio source 702 (FIG. 7). And insome embodiments, the first playback device is configured to operate asa group member in a manner the same as or similar to any of groupmembers 710, 712, and 714 (FIG. 7) described herein, and the secondplayback device is configured to operate in a manner the same as orsimilar to the group coordinator 704 (FIG. 7) described herein.

In some embodiments, an individual packet of the first streamtransmitted from the source device via the first wireless channel andaddressed to the second playback device comprises one or more of (i) aportion of media content and (ii) a sequence identifier and/or atimestamp corresponding to the portion of media content. And in someembodiments, an individual packet of the second stream transmitted fromthe second playback device via the second wireless channel and addressedto the broadcast group comprises one or more of (i) a portion of mediacontent, (ii) a sequence identifier and/or timestamp corresponding tothe portion of media content, and (iii) playback timing corresponding tothe sequence identifier.

In some embodiments, the first stream comprises an A2DP streamtransmitted via the first wireless channel, and the second streamcomprises a CSB broadcast stream transmitted via the second wirelesschannel. However, the first and second streams can be any streamingprotocol disclosed herein, or any other streaming protocol suitable formedia content now known or later developed.

In some embodiments, selectively receiving and/or processing packetsreceived via one of two streams of packets comprising media content instep 802 includes: (i) while receiving packets via the first stream,determining whether the playback device either (a) failed to receive oneor more packets via the first stream or (b) received one or more erroredor otherwise corrupted packets via the first stream; and (ii) inresponse to determining that the playback device either failed toreceive one or more packets via the first stream or received one or moreerrored or otherwise corrupted packets via the first stream, theplayback device activating a radio to receive (and perhaps alsoreceiving) the missing or corrupted/errored packets via the secondstream.

In some embodiments, selectively receiving and/or processing packetsreceived via one of two streams of packets comprising media content instep 802 additionally or alternatively includes: (i) comparing a qualitymetric for the first wireless channel with the quality metric for thesecond wireless channel; (ii) in response to determining that thequality metric for the first wireless channel is better than the qualitymetric for the second wireless channel, choosing to receive and/orprocess (and perhaps also receiving and processing) packets receivedfrom the source device via the first wireless channel and addressed tothe second playback device; and (iii) in response to determining thatthe quality metric for the second wireless channel is better than thequality for the first wireless channel, choosing to receive and/orprocess (and perhaps also receiving and processing) packets receivedfrom the second playback device via the second wireless channel andaddressed to the broadcast group.

In some embodiments, the quality metric is at least one of (i) awireless SNR (Signal-to-Noise Ratio), (ii) a receive power at the firstplayback device, (iii) a BER (Bit Error Rate) or Packet Error Rate(PER), (iv) a transmission rate, (v) a RSSI (Received Signal StrengthIndication), (vi) SINR (Signal-to-Interference-plus-Noise Ratio), and(vii) a PDR (Packet-Delivery Ratio). However other quality metrics forassessing the quality of a wireless transmission link now known or laterdeveloped could be used as well.

In some embodiments, selectively receiving and/or processing packetsreceived via one of two streams of packets comprising media content instep 802 includes: (i) storing data received via the first stream in afirst buffer; (ii) storing data received via the second stream in asecond buffer; (iii) comparing a quality metric for the first wirelesschannel with the quality metric for the second wireless channel; (iii)in response to determining that the quality metric for the firstwireless channel is better than the quality metric for the secondwireless channel, processing data stored in the first buffer; and (iv)in response to determining that the quality metric for the secondwireless channel is better than the quality for the first wirelesschannel, processing data stored in the second buffer. Some embodimentsadditionally include notifying the sender of the second stream of one ormore of (i) which wireless channel of the first and second wirelesschannels has a better quality metric, and/or (ii) which buffer of thefirst and second buffers data is being processed from.

Next, method 800 advances to step 804, which includes coordinatingplayback of the media content in synchrony with one or more otherplayback devices via control messages exchanged with the second playbackdevice via a third wireless channel.

In some embodiments, the control messages exchanged with the secondplayback device via the third wireless channel comprise one or more of(i) clock information of the second playback device and (ii) playbacktiming corresponding to individual sequence identifiers and/ortimestamps, wherein an individual sequence identifier and/or timestampcorresponds to a portion of media content. In some embodiments, thethird wireless channel comprises a Bluetooth Classic or Bluetooth LowEnergy (BLE) link. However, other wireless links suitable for exchangingsignaling data between wireless devices now known or later developedcould be used instead.

In some embodiments, method 800 additionally includes determining atiming offset between a local clock at the first playback device and theclock information of the second playback device.

In some embodiments, coordinating playback of the media content insynchrony with one or more other playback devices via the controlmessages exchanged with the second playback device via the thirdwireless channel in step 804 comprises, for an individual packetcomprising media content: (i) extracting a portion of the media contentfrom the individual packet, wherein the individual packet is receivedvia one of (i-a) the first stream transmitted from the source device viathe first wireless channel and addressed to the second playback device,or (i-b) the second stream transmitted from the second playback devicevia the second wireless channel and addressed to the broadcast groupcomprising the first playback device; (ii) creating an adjusted playbacktime for the media content within the individual packet by adjusting aplayback time for the media content based on the timing offset, whereinthe playback time is one of (ii-a) received via the control messagesexchanged with the second playback device via the third wireless channelor (ii-b) contained within the individual packet received via the secondwireless channel; and (iii) playing the portion of media contentextracted from the individual packet when a local clock at the firstplayback device reaches the adjusted playback time.

VIII. Conclusion

The above discussions relating to playback devices, controller devices,playback zone configurations, and media/audio content sources provideonly some examples of operating environments within which functions andmethods described below may be implemented. Other operating environmentsand configurations of media playback systems, playback devices, andnetwork devices not explicitly described herein may also be applicableand suitable for implementation of the functions and methods.

The description above discloses, among other things, various examplesystems, methods, apparatus, and articles of manufacture including,among other components, firmware and/or software executed on hardware.It is understood that such examples are merely illustrative and shouldnot be considered as limiting. For example, it is contemplated that anyor all of the firmware, hardware, and/or software aspects or componentscan be embodied exclusively in hardware, exclusively in software,exclusively in firmware, or in any combination of hardware, software,and/or firmware. Accordingly, the examples provided are not the onlyways) to implement such systems, methods, apparatus, and/or articles ofmanufacture.

Additionally, references herein to “embodiment” means that a particularfeature, structure, or characteristic described in connection with theembodiment can be included in at least one example embodiment of aninvention. The appearances of this phrase in various places in thespecification are not necessarily all referring to the same embodiment,nor are separate or alternative embodiments mutually exclusive of otherembodiments. As such, the embodiments described herein, explicitly andimplicitly understood by one skilled in the art, can be combined withother embodiments.

The specification is presented largely in terms of illustrativeenvironments, systems, procedures, steps, logic blocks, processing, andother symbolic representations that directly or indirectly resemble theoperations of data processing devices coupled to networks. These processdescriptions and representations are typically used by those skilled inthe art to most effectively convey the substance of their work to othersskilled in the art. Numerous specific details are set forth to provide athorough understanding of the present disclosure. However, it isunderstood to those skilled in the art that certain embodiments of thepresent disclosure can be practiced without certain, specific details.In other instances, well known methods, procedures, components, andcircuitry have not been described in detail to avoid unnecessarilyobscuring aspects of the embodiments. Accordingly, the scope of thepresent disclosure is defined by the appended claims rather than theforegoing description of embodiments.

When any of the appended claims are read to cover a purely softwareand/or firmware implementation, at least one of the elements in at leastone example is hereby expressly defined to include a tangible,non-transitory medium such as a memory, DVD, CD, Blu-ray, and so on,storing the software and/or firmware.

The invention claimed is:
 1. A first playback device comprising: one ormore processors; and at least one tangible, non-transitorycomputer-readable medium comprising program instructions that areexecutable by the one or more processors such that the first playbackdevice is configured to: after receiving one or more indications thatthe first playback device will operate as a group coordinator for agroup comprising the first playback device and at least a secondplayback device, transmit configuration information to at least thesecond playback device comprising: (i) one or more channel configurationdetails for a first wireless channel via which the first playback deviceis to receive a first stream of packets addressed to the first playbackdevice, and (ii) one or more channel configuration details for a secondwireless channel via which the first playback device is to transmit asecond stream of packets addressed to the group comprising at least thesecond playback device, wherein at least one of the first stream ofpackets or the second stream of packets comprises media content; andcoordinate playback of the media content in synchrony by the group viacontrol messages exchanged with at least the second playback device. 2.The first playback device of claim 1, wherein the program instructionsfurther comprise program instructions that are executable by the one ormore processors such that the first playback device is configured to:generate the second stream of packets comprising the media content; andtransmit the second stream of packets comprising the media content tothe group comprising at least the second playback device.
 3. The firstplayback device of claim 1, wherein the one or more channelconfiguration details for the first wireless channel via which the firstplayback device is to receive the first stream of packets addressed tothe first playback device comprises one or more of (i) a channel or linkidentifier, (ii) a frequency hopping sequence for the channel or link,or (iii) a security key to decode transmissions.
 4. The first playbackdevice of claim 1, wherein the one or more channel configuration detailsfor the first wireless channel via which the first playback device is toreceive the first stream of packets addressed to the first playbackdevice comprises information about an Advanced Audio DistributionProfile (A2DP) Bluetooth link between the first playback device and asource device.
 5. The first playback device of claim 1, wherein the oneor more channel configuration details for the second wireless channelvia which the first playback device is to transmit the second stream ofpackets addressed to the group comprising at least the second playbackdevice comprises one or more of (i) a channel or link identifier, (ii) afrequency hopping sequence for the channel or link, or (iii) a securitykey to decode transmissions.
 6. The first playback device of claim 1,wherein the one or more channel configuration details for the secondwireless channel via which the first playback device is to transmit thesecond stream of packets addressed to the group comprising at least thesecond playback device comprises information about Connectionless SlaveBroadcast (CSB) Bluetooth transmissions from the first playback deviceto the group comprising at least the second playback device.
 7. Thefirst playback device of claim 1, wherein an individual packet of thefirst stream of packets received via the first wireless channel andaddressed to the first playback device comprises one or more of (i) aportion of the media content and (ii) a sequence identifiercorresponding to the portion of the media content in the individualpacket.
 8. The first playback device of claim 1, wherein an individualpacket of the second stream of packets transmitted from the firstplayback device via the second wireless channel and addressed to thegroup comprise one or more of (i) a portion of the media content, (ii) asequence identifier corresponding to the portion of the media content inthe individual packet, and (iii) playback timing corresponding to thesequence identifier.
 9. The first playback device of claim 1, whereinthe control messages exchanged with at least the second playback devicecomprise one or more of (i) clock information of the first playbackdevice and (ii) playback timing corresponding to individual sequenceidentifiers, wherein an individual sequence identifier corresponds to aportion of the media content.
 10. The first playback device of claim 1,wherein the first stream of packets comprises an Advanced AudioDistribution Profile (A2DP) stream received via the first wirelesschannel, wherein the second stream of packets comprises a ConnectionlessSlave Broadcast (CSB) stream transmitted via the second wirelesschannel, wherein the control messages exchanged with at least the secondplayback device comprise control messages exchanged via a third wirelesschannel, and wherein the third wireless channel is one of a BluetoothClassic or Bluetooth Low Energy (BLE) link.
 11. A tangible,non-transitory computer-readable medium comprising program instructionsthat are executable by one or more processors such that a first playbackdevice is configured to perform functions comprising: after receivingone or more indications that the first playback device will operate as agroup coordinator for a group comprising the first playback device andat least a second playback device, transmitting configurationinformation to at least the second playback device comprising: (i) oneor more channel configuration details for a first wireless channel viawhich the first playback device is to receive a first stream of packetsaddressed to the first playback device, and (ii) one or more channelconfiguration details for a second wireless channel via which the firstplayback device is to transmit a second stream of packets addressed tothe group comprising at least the second playback device, wherein atleast one of the first stream of packets or the second stream of packetscomprises media content; and coordinating playback of the media contentin synchrony by the group via control messages exchanged with at leastthe second playback device.
 12. The tangible, non-transitorycomputer-readable medium of claim 11, wherein functions furthercomprise: generating the second stream of packets comprising the mediacontent; and transmitting the second stream of packets comprising themedia content to the group comprising at least the second playbackdevice.
 13. The tangible, non-transitory computer-readable medium ofclaim 11, wherein the one or more channel configuration details for thefirst wireless channel via which the first playback device is to receivethe first stream of packets addressed to the first playback devicecomprises one or more of (i) a channel or link identifier, (ii) afrequency hopping sequence for the channel or link, or (iii) a securitykey to decode transmissions.
 14. The tangible, non-transitorycomputer-readable medium of claim 11, wherein the one or more channelconfiguration details for the first wireless channel via which the firstplayback device is to receive the first stream of packets addressed tothe first playback device comprises information about an Advanced AudioDistribution Profile (A2DP) Bluetooth link between the first playbackdevice and a source device.
 15. The tangible, non-transitorycomputer-readable medium of claim 11, wherein the one or more channelconfiguration details for the second wireless channel via which thefirst playback device is to transmit the second stream of packetsaddressed to the group comprising at least the second playback devicecomprises one or more of (i) a channel or link identifier, (ii) afrequency hopping sequence for the channel or link, or (iii) a securitykey to decode transmissions.
 16. The tangible, non-transitorycomputer-readable medium of claim 11, wherein the one or more channelconfiguration details for the second wireless channel via which thefirst playback device is to transmit the second stream of packetsaddressed to the group comprising at least the second playback devicecomprises information about Connectionless Slave Broadcast (CSB)Bluetooth transmissions from the first playback device to the groupcomprising at least the second playback device.
 17. The tangible,non-transitory computer-readable medium of claim 11, wherein anindividual packet of the first stream of packets received via the firstwireless channel and addressed to the first playback device comprisesone or more of (i) a portion of the media content and (ii) a sequenceidentifier corresponding to the portion of the media content in theindividual packet.
 18. The tangible, non-transitory computer-readablemedium of claim 11, wherein an individual packet of the second stream ofpackets transmitted from the first playback device via the secondwireless channel and addressed to the group comprise one or more of (i)a portion of the media content, (ii) a sequence identifier correspondingto the portion of the media content in the individual packet, and (iii)playback timing corresponding to the sequence identifier.
 19. Thetangible, non-transitory computer-readable medium of claim 11, whereinthe control messages exchanged with at least the second playback devicecomprise one or more of (i) clock information of the first playbackdevice and (ii) playback timing corresponding to individual sequenceidentifiers, wherein an individual sequence identifier corresponds to aportion of the media content.
 20. The tangible, non-transitorycomputer-readable medium of claim 11, wherein the first stream ofpackets comprises an Advanced Audio Distribution Profile (A2DP) streamreceived via the first wireless channel, wherein the second stream ofpackets comprises a Connectionless Slave Broadcast (CSB) streamtransmitted via the second wireless channel, wherein the controlmessages exchanged with at least the second playback device comprisecontrol messages exchanged via a third wireless channel, and wherein thethird wireless channel is one of a Bluetooth Classic or Bluetooth LowEnergy (BLE) link.